Friday

February 12, 2016
Number of results: 72,279

**physics**

A ball attached to the end of a string is whirled on a horizontal circle at constant speed. Consider the linear momentum, total energy, and kinetic energy of the ball throughout its motion. Which of the following statements is true? Both linear momentum and kinetic energy are...
*January 6, 2010 by hilary*

**physics # 3**

3. In a perfectly inelastic collision which of the following is conserved, (give the most accurate answer). a.) Linear momentum b.) Kinetic energy c.) Linear momentum d.) Total mechanical energy, (KE +PE) e.) Heat energy
*August 7, 2007 by gomez*

**Physics**

You drop an egg from rest with no air resistance. As it falls, a. only its momentum is conserved. b. only its kinetic energy is conserved. c. both its momentum and its mechanical energy are conserved. d. its mechanical energy is conserved, but its momentum is not conserved
*March 5, 2011 by Joe *

**physics**

12. Which of the following statements is correct for a particle moving in a horizontal circle with constant angular velocity? A. The linear momentum is constant but the kinetic energy varies. B. The kinetic energy is constant but the linear momentum varies. C. Both kinetic ...
*November 1, 2013 by shanza*

**Physics**

The 9-ball travelling and strikes the 13-ball, which is of equal mass and at rest. If this is an elastic collision, which statement below is true? Marks 3+4 = 7 a) All of the 9-ball’s energy and momentum are transferred to the 13-ball. b) All of the 9-ball’s energy and some of...
*November 19, 2015 by Asma *

**Physics - drwls?**

A 2000 kg truck traveling north at 38 km/hr turns east and accelerates to 55 km/hr. What is the change in the truck's kinetic energy? What is the magnitude of the change in the linear momentum of the truck? What is the direction of the change in linear momentum of the truck? (...
*March 19, 2007 by winterWX*

**physics**

Determine for each of the following statements whether it is always true or can be false. In a perfectly inelastic collision, the kinetic energy is conserved. Kinetic energy is conserved in an elastic collision. Two objects of different masses but moving at the same velocity ...
*March 2, 2012 by Katie*

**Physics**

Find the linear momentum and kinetic energy of a bullet of mass 4.80e-2 kg moving at a speed of 320 m/s. I found the linear momentum to be 15.36 by doing m*v but I can't figure out the kinetic energy.
*October 16, 2011 by Kellie*

**Physics.**

What is the transfer mechanism of energy, momentum, and angular momentum?
*November 27, 2011 by Kristin*

**Physics**

A hydrogen atom is in its third excited state (n=4). Using Bohr theory of the atom calculate (a) the radius of the orbit, (b) the linear momentum of the electron, (c) the angular momentum of the electron (d) the kinetic energy (e) the potential energy, and (f) the total energy...
*April 28, 2012 by Chi*

**physics**

A gun is fired vertically into a 1.55 kg block of wood at rest directly above it. If the bullet has a mass of 21.0 g and a speed of 190 m/s, how high will the block rise into the air after the bullet becomes embedded in it? i don't even know where to begin... would it have ...
*October 31, 2006 by Haley*

**physics**

In a fully random distribution, we can determine the most probable state from what two quantities? Answer a. The number of particles and the net momentum. b. The number of particles and the total energy. c. The net momentum and the total energy. d. the total potential and the ...
*October 15, 2010 by jim*

**Physics**

A 1200 kg car is moving on the freeway at 65 mph. (A) find the magnitude of its momentum and its kinetic energy in SI units. (b) if a 2400 kg SUV has the same speed asthe 1200 kg car, how much momentum and kinetic energy does it have?
*June 22, 2009 by Sarah*

**Physics**

A bullet with a mass of 55 grams moving with a speed of 100 m/s slams into and wedges in a 1.9 kilogram block of wood supported by a string initially at rest. Which one, conservation of energy or conservation of momentum, can be applied to this situation? Why? I think it's ...
*October 14, 2010 by Fred*

**physics**

Which of the following statements is true for an inelastic collision? A. Both momentum and kinetic energy are conserved. B. Momentum is conserved, but kinetic energy is not conserved. C. Kinetic energy is conserved, but momentum is not conserved. D. The amount of momentum lost...
*March 5, 2011 by Joe *

**Physics**

Which of the following statements is true for an elastic collision? A. Both momentum and kinetic energy are conserved. B. Momentum is conserved, but kinetic energy is not conserved. C. Kinetic energy is conserved, but momentum is not conserved. D. The amount of momentum lost ...
*March 5, 2011 by Joe *

**Physics**

Object A has mass mA = 9 kg and initial momentum A,i = < 19, -7, 0 > kg · m/s, just before it strikes object B, which has mass mB = 12 kg. Just before the collision object B has initial momentum B,i = < 5, 6, 0 > kg · m/s. Consider a system consisting of both ...
*November 21, 2010 by What does this even mean!?*

**physics**

the speed of the fastest pitched baseball was 45 m/s, and the ball's mass was 145 g. (a) What was the magnitude of the momentum of this ball, and how many joules of kinetic energy did it have? (b) How fast would a 57 gram ball have to travel to have the same amount of (i) ...
*October 28, 2009 by sarah*

**Physics Momentum**

1) Two 1 kg balls move away from each other, one traveling 5 m/s to the right, the other 5 m/s to the left. What is the magnitude of the total momentum of the system? 2) Two 1000 kg cars drive east; the first moving at 20 m/s, the second at 40 m/s. What is the magnitude of the...
*February 20, 2013 by Isis*

**physics**

A cart of mass 340 g moving on a frictionless linear air track at an initial speed of 1.2 m/s undergoes an elastic collision with an initially stationary cart of unknown mass. After the collision the first cart continues in its original direction at .66m/s. a) what is the mass...
*March 4, 2007 by Chris*

**Physics**

A satellite of mass m is in Keplerian orbit around a parent body of mass M >>m. The satellite has total energy E and angular momentum l, where angular momentum is measured about the parent body and the zero of potential energy is at infinity. Detnermine the semimajor ...
*May 10, 2011 by Carole*

**Physics**

A satellite of mass m is in Keplerian orbit around a parent body of mass M >>m. The satellite has total energy E and angular momentum l, where angular momentum is measured about the parent body and the zero of potential energy is at infinity. Detnermine the semimajor ...
*May 10, 2011 by Ferdinand*

**Physics**

A satellite of mass m is in Keplerian orbit around a parent body of mass M >>m. The satellite has total energy E and angular momentum l, where angular momentum is measured about the parent body and the zero of potential energy is at infinity. Detnermine the semimajor ...
*May 10, 2011 by Carole*

**physics**

A skater spinning with angular speed of 1.5 rad/s draws in her outstretched arms thereby reducing her moment of inertia by a factor a 3. a) Find her final angular speed. b)What is the ratio of her final angular momentum to her initial angular momentum? c) Determine the ratio ...
*December 2, 2010 by Kevin*

**Physics Please check my answer**

1. Which of the following are conserved in a totally inelastic collision? Only momentum Only kinetic energy Both momentum and kinetic energy Neither momentum nor kinetic energy <--- It depends on the objects. 2. Two skaters stand face to face. Skater 1 has a mass of 55 kg, ...
*January 11, 2014 by unknown*

**Physics Work and Energy, Momentum**

Let g be the acceleration due to gravity at the surface of a planet of radius R. Which of the following is a dimensionally correct formula for the minimum kinetic energy K that a projectile of mass m must have at the planet's surface if the projectile is to escape from the ...
*May 13, 2007 by Kelly*

**Physics**

two objects collide when sliding on a fricitonless horizontal surface. Which quantity is conserved during their collision? a) velocity b) momentum of both objects c)energy d) momentum of each object isn't c) or b) correct? I really think it's c)
*November 14, 2007 by Andrea*

**physics**

i need some help wih this, thanks!! Blocks A and B are moving toward each other along the x axis. A has a mass of 2.0 kg and a velocity of 50 m/s ( in the positive x direction ), while B has a mass of 4.0 kg and a velocity of -25 m/s ( in the negative x direction). They suffer...
*August 7, 2007 by Damon*

**physics**

When a cannon fires a cannonball, the cannon will recoil backward because the a) energy of the cannonball and the cannon is conserved b) momentum of the cannonball and cannon is conserved c)energy of the cannon is greater than the energy of the cannonball d) momentum of the ...
*October 24, 2007 by Tammy*

**Physics please explain**

In the quantum mechanical picture of the hydrogen atom, the orbital angular momentum of the electron may be zero in any of the possible energy states. For which energy state must the orbital angular momentum be zero? n = 1 n = 2 n = 3 n = 4 Give your reasoning. I am not sure ...
*December 14, 2007 by Mary*

**physics**

write down in terms of the mass m and the velocity v of the body, expressions for i) momentum ii) the kinetic energy use your answer to (b) to help calculate the mass and the velocity of the ball momentum is mass*velocity Kinetic energy is 1/2 mass*velocity squared.
*October 16, 2006 by Kim*

**physics**

a 2646lb car is moving on the freeway at 69 mph. (a) Find the magnitude of its momentum and its kinetic energy in SI units. (b) At what speed, in m/s, will the car's momentum be half of what it is in part (a). (c) At what speed, in m/s, will the cats kinetic energy be half of ...
*January 22, 2016 by chyenne*

**physics**

Let a force of 1500 Newtons act through a distance of 200 meters on a 1500 kg car which starts from rest. a. What is the work done? b. What is the final velocity? c. What is the car's momentum? d. What is the car's change in momentum? e. What is the car's Kinetic Energy? f. ...
*November 14, 2011 by Ryan*

**physics**

a 1200kg car is moving on the freeway at 30 m/s. (a) Find the magnitude of its momentum and its kinetic energy in SI units. (b) At what speed, in m/s, will the car's momentum be half of what it is in part (a). (c) At what speed, in m/s, will the cars kinetic energy be half of ...
*January 22, 2016 by van*

**physics-help please........**

The momentum and the kinetic energy of particle A is eight times and nine times the momentum and the kinetic energy of particle B, respectively. What is the ratio of the mass of particle A to that of particle B?
*October 30, 2011 by lost*

**Science**

We are studying energy my questions What happens to the momentum of a car when it comes to a stop? The momentum is transfered to the Earth. Momentum is always conserved. What happens to the momentum of a car when it comes to a stop?
*January 9, 2007 by Mae*

**physics**

please check my answers what are the SI units for momentum? kg*m/s which of the following is not involved in hitting a tennis ball? a. kinetic energy b. chemical potential energy c. gravitational potential energy d. elastic potential energy i picked B How much power is ...
*February 16, 2009 by y912f*

**momentum/impulse**

The following data concerns a tennis ball at a given instant before it is struck by a tennis racket; horizontal momentum of tennis ball= 2.4Ns kinetic energy of ball= 45J a) why is correct to give the direction of the momentum but not the kinetic energy b) write down in terms ...
*October 15, 2006 by Kim*

**PHYSICS! PLEASE!**

The following data concerns a tennis ball at a given instant before it is struck by a tennis racket; horizontal momentum of tennis ball= 2.4Ns kinetic energy of ball= 45J a) why is correct to give the direction of the momentum but not the kinetic energy b) write down in terms ...
*October 15, 2006 by Kim*

**physics**

work & energy homework problems: please help me =] my teacher is bad a teaching how to do stuff =/ 1)A 5.000kg plastic ball moves with a velocity of 10.00 m/s x. It collides with a second plastic ball of mass of 10.00kg at rest. The collision is completely elastic. find: a)the...
*December 16, 2007 by alissa*

**Physics**

When a skydiver jumps from a plane and achieves terminal speed. Which quantity remains constant? (a) Momentum (b) kinetic energy (c) potential energy (d) both a and b (e) both a and c I say kinetic energy, am i right?
*April 4, 2009 by James*

**physics**

You accelerate your 1500 Kg from 2 m/s to 12 m/s in 2 seconds. How do you determine the cars acceleration initial momentum final momentum change in momentum the force required to do this?
*January 11, 2016 by Kelley*

**Physics**

Please Help ! A child throws a snowball at a tree and it sticks to the tree. Does this motion defy the Law of Conservation of Momentum? Explain. The Law of Conservation of Energy states: "If there is no net force acting on a system of objects, the total momentum in that system...
*November 9, 2009 by Rachel *

**physics**

You accelerate your 1500 Kg car from 2 m/s to 12 m/s in 2 seconds. How do you determine the cars acceleration initial momentum final momentum change in momentum the force required to do this?
*January 11, 2016 by Kelley*

**PHYSICS - PLEASE HELP**

Part A: A cardinal (Richmondena cardinalis) of mass 4.50×10^−2 kg and a baseball of mass 0.142 kg have the same kinetic energy. What is the ratio of the cardinal's magnitude p(c) of momentum to the magnitude p(b) of the baseball's momentum? Part B: A man weighing 650 N ...
*November 28, 2012 by Mary*

**PHYSICS - PLEASE HELP**

Part A: A cardinal (Richmondena cardinalis) of mass 4.50×10^−2 kg and a baseball of mass 0.142 kg have the same kinetic energy. What is the ratio of the cardinal's magnitude p(c) of momentum to the magnitude p(b) of the baseball's momentum? Part B: A man weighing 650 N ...
*November 30, 2012 by Anonymous*

**physics**

Which one of the following statements is true for two bodies having same kinetic energy but different masses? a. they have same velocity b. they have same momentum c. the momentum of smaller mass body is smaller than the other d. the momentum of smaller mass body is larger ...
*June 14, 2012 by Jeremy *

**physics**

Consider a single photon of red laser light, with wavelength of 633 nm (nano is 10-9). What energy does this carry? What momentum? How does the energy compare to typical atomic energies of a few times 10-19 J?
*April 17, 2011 by maggie*

**Physics**

Part A: A cardinal (Richmondena cardinalis) of mass 4.50×10^−2 kg and a baseball of mass 0.142 kg have the same kinetic energy. What is the ratio of the cardinal's magnitude p(c) of momentum to the magnitude p(b) of the baseball's momentum? Part B: A man weighing 650 N ...
*November 27, 2012 by Mary*

**Physics**

Part A: A cardinal (Richmondena cardinalis) of mass 4.50×10^−2 kg and a baseball of mass 0.142 kg have the same kinetic energy. What is the ratio of the cardinal's magnitude p(c) of momentum to the magnitude p(b) of the baseball's momentum? Part B: A man weighing 650 N ...
*November 28, 2012 by M*

**physics**

(a) What is the frequency of a photon whose energy is 3.5 times the rest energy of an electron? (b) What would be the linear momentum of the photon?
*April 27, 2012 by joe*

**Physics - drwls**

Posted by winterWX on Monday, March 19, 2007 at 11:51pm. A 2600 kg truck traveling north at 38 km/hr turns east and accelerates to 55 km/hr. What is the change in the truck's kinetic energy? What is the magnitude of the change in the linear momentum of the truck? What is the ...
*March 22, 2007 by winterWX*

**Physics**

A skater spinning with angular speed of 1.5 rad/s draws in her outstretched arms thereby reducing her moment of inertia by a factor a 3. a) Find her angular speed. b)What is the ratio of her final angular momentum to her initial angular momentum? c)Did her mechanical energy ...
*December 2, 2010 by Tarren*

**Physics**

Neutrons have a rest mass of 1.6749*10-27 kg (equivalent to 939.6 MeV). If a certain neutron has a total energy of 949 MeV, what are its relativistic mass energy in MeV, its speed in m/s, its kinetic energy in MeV, and its momentum in kg.m.s-1?
*November 28, 2013 by Jane*

**Physical science**

Is it possible for an object to have more kinetic energy but less momentum than the other object? Less kinetic energy but more momentum? *i know the answer to both questions is yes, however, i cannot think of examples ??
*February 11, 2012 by Jess*

**Physics ~MOMENTUM~**

a) what is the momentum of a 4.6 kg baseball moving at 1.4 m/s? b) a child is running with a velocity of 4.5 m/s and has a momentum of 120 kgm/s. What is the child's mass? ~formula~ P=mv help please!!!
*February 16, 2013 by Isis*

**Physics (MOMENTUM)**

Please, help me answer this question. Two balls are moving in the same direction. Ball A has half the mass of ball B, and is moving at twice its speed. (a) Which ball has the greater momentum? (b) Which ball has greater kinetic energy? Thank you.
*May 2, 2013 by Kathy*

**College Physics**

The electron-volt, eV, is a unit of energy (1eV = 1.602 ·10–19 J, 1 MeV = 1.602 ·10–13 J). Since the unit of momentum is an energy unit divided by a velocity unit, nuclear physicists usually specify momenta of nuclei in units of MeV/c, where c is the speed of light (c = 2.998...
*October 13, 2013 by Kimmy*

**Physics**

An electron has a total energy of 2.8 MeV. What is its momentum?
*May 6, 2009 by Anonymous*

**physics**

A hydrogen atom is in its n = 6 excited state. Determine, according to quantum mechanics, each of the following: (a) The total energy =eV (b) The magnitude of the maximum angular momentum the electron can have in this state =J s (c) The maximum value that the z component of ...
*December 1, 2006 by MIke*

**physics**

A hydrogen atom is in its n = 6 excited state. Determine, according to quantum mechanics, each of the following: (a) The total energy =eV (b) The magnitude of the maximum angular momentum the electron can have in this state =J s (c) The maximum value that the z component of ...
*December 2, 2006 by MIke*

**Physics**

A relativistic proton has a momentum of 1.0×10^-17 kg ∙ m/s and a rest energy of 0.15 nJ. What is the kinetic energy of this proton? (c = 3.00 × 108 m/s, mass of proton = 1.67 × 10-27 kg)
*September 20, 2014 by Justin*

**Physics**

A relativistic proton has a momentum of 1.0×10^-17 kg ∙ m/s and a rest energy of 0.15 nJ. What is the kinetic energy of this proton? (c = 3.00 × 108 m/s, mass of proton = 1.67 × 10-27 kg)
*September 21, 2014 by Ashley*

**physics**

Hello, I'm trying to figure out which of the following statements are TRUE. I suspect that 2, 6, 8 are true...and that there is one more that is true, but not sure which one? Thanks! It is impossible to have a collision between two objects in which the center-of-mass of the ...
*October 29, 2011 by John*

**Physics**

Hello, I'm trying to figure out which of the following statements are TRUE. I suspect that 2, 6, 8 are true...and that there is one more that is true, but not sure which one? Thanks! It is impossible to have a collision between two objects in which the center-of-mass of the ...
*October 29, 2011 by Anonymous*

**Physics**

Two objects are mocing about so that their total momentum is zero. What can be said about their kinetic energy? Choose the most descriptive answer. a. the kinetic energy must be greater than zero b. the kinetic energy must be negative c. the kinetic energy must be equal to or ...
*March 21, 2011 by Paige*

**Physics**

Consider an isolated system consisting of two masses, each of which has a velocity vector in two dimensions. When these two masses collide the total momentum of the system is conserved. (a) Show that if the total momentum of the system is conserved then the component momenta ...
*March 30, 2014 by Tim*

**special relativity **

A projectile of rest mass M1, total energy E1, and momentum p1, is directed at a stationary target of mass m2. Find the the velocity of the centre-of-momentum frame .
*June 7, 2011 by Deforest *

**Please help with Physics Quickly**

1. How are impulse and momentum related? (Points : 1) Impulse is the change in momentum of an object. Momentum is the change in impulse acting on an object. Impulse and momentum are always equal in magnitude. Impulse and momentum are the same thing. Question 2. 2. Which of ...
*January 27, 2014 by Anna*

**Physics**

A 125 ball has a kinetic energy 33.6 What is the magnitude of it's momentum? What is the speed?
*December 5, 2012 by Amanda*

**physics**

. If the momentum of an object is tripled, its kinetic energy will change by what factor?
*October 19, 2013 by fola*

**physics**

If the kinetic energy of an automobile triples because of a speed change, it momentum is ?
*April 21, 2015 by titu*

**Physics**

fill in the blank ( Energy and momentum unit) 1. the work done to stretch a spring is not equal to the to force multiplied by displacement because force is ____ as the spring stretches 2. A child goes down a slide at the playground, gaining speed as she goes. Her momentum ____...
*July 3, 2014 by Liz*

**physics**

Car 1 approaches an intersection with a momentum of p1i=(11,000 kg*m/s)x + (-370 kg*m/s)y. Car 2 approaches the same intersection with momentum p2i= (4,000 kg*m/s)x + (2470 kg*m/s)y. The cars collide and immediately the momentum of Car2 is p2f= (2100 kg*m/s)y. What is the ...
*October 13, 2010 by Anonymous*

**Physics**

Bernoulli's equation is an expression of: the conservation of mass the conservation of total energy the conservation of kinetic energy the conservation of momentum the conservation of velocity My ans: the equation states that it should be a constant when there is a streamline ...
*December 2, 2009 by Nikita*

**physics**

a 2.5 kg rifle fires a 20 g bullet at 400 m/s. What is the magnitude of the recoil velocity of the rifle? I still don't understand. Could you please help with a formula? Thank you. physics - drwls, Monday, February 7, 2011 at 6:38pm Try using conservation of momentum. recoil ...
*February 7, 2011 by Sejul*

**Physics - Momentum**

Define momentum qualitatively and quanititatively. (qualitatively - a measure of an object's mass to resist changes in its velocity or acceleration. Is this correct? How do I define momentum quantitatively)
*August 25, 2010 by Shaila*

**physics**

Suppose a ball of putty moving horizontally with 1kg.m/s of momentum collides and sticks to an identical ball of puffy moving vertically with 1 kg.m/s of momentum. Why is their combined momentum not simply the arithmetic sum, 2 kg.m/s?
*November 8, 2013 by Anonymous*

**Physics**

A billiard ball of mass m = 0.250 kg hits the cushion of a billiard table at an angle of θ1 = 56.2° and a speed of v1 = 24.8 m/s. It bounces off at an angle of θ2 = 71.0° and a speed of v2 = 10.0 m/s. (a) What is the magnitude of the change in momentum of the ...
*October 28, 2014 by Anonymous*

**Physics - Angular Momentum**

When the angular momentum changes, the 'change' in the angular momentum vector (ie. dL) is ____. [a.] perpendicular to the torque vector. [b.] parallel to the angular momentum vector. [c.] parallel to the torque vector. .. im confused on this one.. i think it's [A]. am i right...
*April 8, 2007 by COFFEE*

**physics(check my answer)**

A 60.0 kg person bends his knees and then jumps straight up. After his feet leave the floor, his motion is unaffected by air resistance and his center of mass rises by a maximum of 14.9 cm. Model the floor as completely solid and motionless. (a) Does the floor impart impulse ...
*March 31, 2010 by phys*

**physics**

A car is released from rest on a frictionless inclined plane. (Figure: twitpic com/e8nkhj) Calculate the momentum pi at the end of the plane in terms of measured quantities x, y, l, and m. Assume θ is very small so that h/l ~= y/x. (Hint: use conservation of energy and K...
*July 21, 2014 by Anonymous*

**physics intro**

A ball of mass 0.50 kg is thrown straight up at 6.0 m/s. (a)What is the initial momentum of the ball? (b) What is the momentum of the ball at its peak? (c)What is the momentum of the ball as it hits the ground
*October 7, 2014 by ben green*

**physics**

Two astronauts, each having a mass of 78.5 kg, are connected by a 10.0-m rope of negligible mass. They are isolated in space, moving in circles around the point halfway between them at a speed of 5.50 m/s. Treating the astronauts as particles, calculate each of the following...
*December 1, 2012 by heather*

**Physics**

A photon of energy E strikes an electron at rest undergoes pair production, producing a positive electron(positron) and an electron, photon+electron produce positron+electron+electron The two electrons and the positron move off with identical momenta in the direction of the ...
*March 22, 2011 by Abby*

**Science**

Which of the following statements is true about a collison between two cars? The total momentum after the collision is the same as the total momentum befor the collision *** The total momentum after the collision is greater than the total momentum beforethe collision The ...
*March 11, 2015 by Kennabug*

**Physics**

Two rollerbladers throw a frisbie back and forth on a frictionless surface. Which does not change? a. Momentum of an individual rollerblader b. Momentum of the frisbie c. Momentum of the system consisting of the frisbie and rollerbladers throwing the ball d. Momentum of the ...
*April 12, 2009 by Jacob*

**Physics **

A solid metal ball and a hollow plastic ball of the same external radius are released from rest in a large vacuum chamber. When each has fallen 1 m, they both have the same 1. momentum. 2. inertia. 3. speed. 4. change in potential energy. 5. kinetic energy.
*December 2, 2012 by Emily*

**Physics (very long question)**

Two astronauts (Fig. P8.68), each having a mass of 84.0 kg, are connected by a 10.0 m rope of negligible mass. They are isolated in space, moving in circles around the point halfway betwen them at a speed of 5.80 m/s. Treating the astronauts as particles, calculate each of the...
*November 18, 2010 by Anonymous*

**Physics**

A 0.25-kg ball is attached to a 26-cm piece of string. The ball is first raised so that the string is taut and horizontal, then the ball is released so that, at the bottom of its swing, it undergoes an elastic head-on collision with a 0.21-kg ball that is free to roll along a ...
*April 28, 2009 by Lucy X*

**physics**

Two hypothetical planets of masses m1 and m2 and radii r1 and r2, respectively, are nearly at rest when they are an infinite distance apart. Because of their gravitational attraction, they head toward each other on a collision course. Note: Both the energy and momentum of the ...
*March 11, 2011 by Rachel*

**Physics **

The rotational inertia of a collapsing star changes to one third its initial value while conserving angular momentum. What is the ratio of the new rotational kinetic energy to the initial kinetic energy?
*August 11, 2015 by Yoyo*

**physics**

5. An object that has kinetic energy must have A) momentum. B) acceleration. C) a force applied to it. D) All of these. E) None of these.
*February 21, 2012 by britches*

**physics**

5. An object that has kinetic energy must have A) momentum. B) acceleration. C) a force applied to it. D) All of these. E) None of these.
*February 21, 2012 by britches*

**physics**

let p and E denote the linear momentum and energy of emitted photon respectively if the wavelength of incident radiation is increased----
*February 27, 2013 by prasad*

**dyanamics**

Which one of the following statements is correct? (a) Energy and work are scalars (b) Force and work are vectors (c) Energy, momentum and velocity are vectors (d) Force, momentum and velocity are scalars
*August 3, 2012 by raja*

**physics conservation of momentum**

A 0.5 kg ball is thrown horizontally towards a wall with a speed of 10 m/s. The initial velocity is chosen to be the positive x-direction for this question. The ball horizontally rebounds back from the wall with a speed of 10 m/s in the negative x-direction. What is momentum ...
*November 8, 2008 by rachel*

**Physics**

A nucleus, initially at rest, decays radioactivly, leaving a residual nucleus. In the process, it emits two paricles horizontally: an electron with momentum 9.0 x 10^-21 kg m/s [E] and a neutrino with momentum 4.8 x 10^-21 kg m/s [S]. In what direction does the residual ...
*November 5, 2010 by Jordge*

**physics**

1) What average power is required for a runner with a mass of 85 kg to reach a speed of 8 m/s from a stationary start during a time of 2 s? 2) A 1000 kg car travels east at 30 m/s and collides with a 3400 kg truck travelling south at 20 m/s. After the collision the two ...
*March 29, 2015 by k*

**physics**

refer to a situation where you exert a force F on a crate of mass M, moving it at a speed v a distance d across a floor in a time interval t. The quantity F d/t is? a.)kinetic energy of the crate b.)potential energy of the crate c.)linear momentum of the crate d.)work you do ...
*July 30, 2011 by Tarissa*