Friday

April 24, 2015

April 24, 2015

**physics**

a 70 kg block rests on the earth's surface. How much energy is required to move the block very far from the earth, ending up at rest again?
*Sunday, March 22, 2015 at 2:18am*

**8**

You and your friends are doing physics experiments on a frozen pond that serves as a frictionless, horizontal surface. Sam, with mass 70.0kg , is given a push and slides eastward. Abigail, with mass 55.0kg , is sent sliding northward. They collide, and after the collision Sam ...
*Sunday, March 22, 2015 at 12:03am*

**Physics**

Two balls of equal mass (400g each) undergo a collision. One ball is initially stationary. After the collision, the velocities of the balls make angles of 22.5 degrees and 35.9 degrees relative to the original direction of the motion of the moving ball. If the initial velocity...
*Sunday, March 22, 2015 at 12:03am*

**physics**

in a game of billiard , a collision occurs between two marble balls of different mass. one ball 400g is initially at rest. After the collision, this ball acquires a velocity of 1.40m/s at an angle of 37 degrees from the original direction of the motion of the other ball (500g...
*Saturday, March 21, 2015 at 11:59pm*

**Physics**

A 130kg mail bag hangs by a vertical rope 3.9m long. A postal worker then displaces the bag to a position 2.2m sideways from its original position, always keeping the rope taut.
*Saturday, March 21, 2015 at 11:24pm*

**Physics**

A rock is thrown directly upward from the edge of the roof of a building that is 35.3 meters tall. The rock misses the building on its way down, and is observed to strike the ground 4.00 seconds after being thrown. Neglect any effects of air resistance. With what speed was the...
*Saturday, March 21, 2015 at 10:34pm*

**Physics**

A motor boat is traveling at a speed of 2.4 m/s shuts off its engine at t=0. How far does it travel before coming to a rest if it is noted that after 3 seconds its speed has dropped to half of its original value? Assume that the drag force of the water is proportional to v. (R...
*Saturday, March 21, 2015 at 8:57pm*

**Physics**

a 2.00 kg object has a velocity of 4.00i -3.00j m/s. What is the kinetic energy at this moment? What is the net work done on the object if its velocity change 6.00i +2.00j m/s
*Saturday, March 21, 2015 at 8:57pm*

**Physics**

So...the question is that a coil spring has a force constant of k = 4.0 lb/in. When the spring's axis is inclined at an angle 30 degrees form horizontal, a Weight = 2.0 oz ball is propelled to a height of 6.0 ft. By how much must the spring have been compressed initially...
*Saturday, March 21, 2015 at 8:55pm*

**Physics **

A motor boat is traveling at a speed of 2.4 m/s shuts off its engine at t=0 . How far does it travel before coming to rest after 3 seconds it's speed have dropped to half of its original value ? Assume that the drag force of the water is proportional to v ( R = -bv)
*Saturday, March 21, 2015 at 8:37pm*

**Physics **

a car goes over a circular hill of 50m radius at a constant speed of 20m/sec . What is the force of the car on the 600N driver at the top of the hill.?
*Saturday, March 21, 2015 at 8:23pm*

**physics**

How many circus balloons will it take to lift a 80.0 kg person? The pressure is 1.00 atmospheres. The temperature is 298 K. The air is composed of 20.0% oxygen and 80.0% nitrogen. Each balloon is a perfect sphere, 40 cm in diameter, filled with helium gas (also at 1.00 ...
*Saturday, March 21, 2015 at 6:48pm*

**Physics**

A pendulum string has a length l = 4.0 ft. When the pendulum ball is released at 90 degrees to the vertical, it will swing down. A nail is located distance d below the point of suspension of the pendulum. Show that d must be at least 0.6l if the ball is to swing completely ...
*Saturday, March 21, 2015 at 1:17pm*

**mathematical physics**

Using Green's theorum evaluate the integral [ integration from c x^2ydx-xy^2dy] where c is the closed curve along the circle. x^2+y^2 = 4
*Saturday, March 21, 2015 at 12:25pm*

**mathematical physics**

Using Divergence theorum evaluate the flux integrate from s vector A.vector D's where A =xi^+yj^+zk^ and s is the complete surface of the hemisphere which has its centre at the origin and the origin and a radius of 6 units.
*Saturday, March 21, 2015 at 12:20pm*

**mathematical physics**

Calculate the work done by a force vector F = y^2z^3i^+2xyz^3j^+3xy^2z^2k^ in moving an object along the path defined by the parametric equation x = t, y = t, z = t between the points A( t =0 ) and B( t = 1).
*Saturday, March 21, 2015 at 12:11pm*

**mathematical physics**

Determine the scale factors for an orthogonal coordinate system ( s, t, v ) whose coordinates are related to the cartesion by following equations: x = 2st:, y = s^2-t^2:, z = v Also write down an expression for the square of the arc element.
*Saturday, March 21, 2015 at 12:03pm*

**mathematical physics**

Obtain the curl of the following vector field in spherical polar coordinates : vector A = x( xi^+yj^+zk^)
*Saturday, March 21, 2015 at 11:14am*

**mathematical physics**

Determine whether the following vector field is incompressible or irrotational at the point (0, 1, 2) vector F =[x/x^2+y^2+z^2]i^ +[y/x^2+y^2+z^2]j^+[z/x^2+y^2+z^2]k^
*Saturday, March 21, 2015 at 11:10am*

**physics**

Why is parallax method not useful for measuring the distances of stars more than 100 light years away?
*Saturday, March 21, 2015 at 11:06am*

**physics**

A spring balance has a scale that reads from 0to50 kg.The length of the scale is 20cm.A body suspended from this balance,when displaced & released, oscillates with period of 0.6 s.What is the weight of the body?
*Saturday, March 21, 2015 at 11:06am*

**mathematical physics**

Determine the directional derivative of phi =xy^z in the direction i^-2j^+2k^ at the point (3, 1, -1)
*Saturday, March 21, 2015 at 11:01am*

**mathematical physics **

Given two vector function vector a(t)=(2t+3)i^+(t^2-2)j^+tk^ and vector b(t)=(4-t)i^+(3t^3+1)j^+(2t-1)k^, determine the derivative of vector a(t).vector b(t) at t=1.
*Saturday, March 21, 2015 at 10:57am*

**physics**

A wheel has turned through 120 revs in 10 s after starting. find the angular acceleration.
*Saturday, March 21, 2015 at 10:52am*

**physics**

The throttle of an electric train is shut off at a speed of 48 km/h. The total mass of the train is 81 tonne and the combined resistance force is 90 newtons per tonne. Find how long it will take for the train to stop.
*Saturday, March 21, 2015 at 10:51am*

**physics**

If, after rotating for some time at constant angular velocity of 72 rad/s, brakes are applied to the flywheel producing retardation of 4 rad/s2 , determine the time taken to reduce its angular velocity to 40 rad/s.
*Saturday, March 21, 2015 at 10:49am*

**physics**

A 1 tonne caravan is being towed by a car which provides a constant drawbar pull of 40 N. If the resistance to motion is 20 N, calculate the acceleration of the car and the caravan.
*Saturday, March 21, 2015 at 10:49am*

**mathematical physics**

Show that the angular momentum vector(L)=vector(r)×vector(p) vector is an axial vector
*Saturday, March 21, 2015 at 10:49am*

**physics**

The five engines of the first stage of a launch vehicle provide a total thrust of 31.5 x 106 newtons to the space vehicle (launch vehicle and spacecraft). Assuming the acceleration is uniform, calculate the acceleration of the 2.764 x 106 kg space vehicle after lift-off. The ...
*Saturday, March 21, 2015 at 10:48am*

**mathematical physics**

For any two vectors u^ and v^ show that: (u^.v)^2-[(u^×v^)].u^= u^2v^2
*Saturday, March 21, 2015 at 10:42am*

**physics**

If a mass of gasoline occupies 70.01 at 20Â°C, What is the volume at 35Â°C?
*Saturday, March 21, 2015 at 8:17am*

**Physics**

A 130kg mail bag hangs by a vertical rope 3.9m long. A postal worker then displaces the bag to a position 2.2m sideways from its original position, always keeping the rope taut.
*Saturday, March 21, 2015 at 7:47am*

**physics**

Show that the angular momentum L=r¡Áp vector is an axial vector
*Saturday, March 21, 2015 at 7:06am*

**physics**

the mass of the sun is 2×10^30kg.the mass of a proton is 2×10^-27kg.if the sun was made only of protons.calculate the number of protons in the sun?
*Saturday, March 21, 2015 at 6:30am*

**Medical physics**

A silver cube (density of silver is 10 g/cm3) with side length of 3 cm weighs more than an aluminium cube (density of aluminium is 2.96 g/cm3) with side length of 4 cm. The cubes are each suspended by a string and allowed to be completely immersed in two identical jars ...
*Saturday, March 21, 2015 at 3:56am*

**physics**

an aluminium sphere of 20cm diameter is heated from 0¡ãc to100¡ãc. what is the change in its volume?
*Friday, March 20, 2015 at 7:58pm*

**physics**

A camera with a lens of focal length 10 cm takes a picture of a 160 cm girl standing 24.0 m away. What is the approximate height of the image?
*Friday, March 20, 2015 at 4:47pm*

**physics**

for long distance transmission of electricity, voltages of 1- 26 kv at the generator are stepped up high levels, 230-768 kv. in stepping up from 1 kv to 768 kv, if there are 200 turns of transformer wireon the primary, how many turns will the secondary contain?
*Friday, March 20, 2015 at 3:19pm*

**physics**

small toy car draws a 0.50mA from a 3.0 V nickel-cadmium(NiCd) battery. In 10 min of operation, (a) how much charge flows through the toys car? (b) How much energy is lost by the battery?
*Friday, March 20, 2015 at 2:29pm*

**physics**

A 25.0 g silver spoon at 20.0 C is placed in a cup of coffee initially at 90 C. How much heat does the spoon absorb from the coffee as the spoon warms up to 89 C? (C Silver - 230 J/kg C) Show all work.
*Friday, March 20, 2015 at 2:26pm*

**physics**

A long solenoid that has 990 turns uniformly distributed over a length of 0.410 m produces a magnetic field of magnitude 1.00 multiply.gif 10-4T at its center. What current is required in the windings for that to occur?
*Friday, March 20, 2015 at 2:25pm*

**physics**

A 47.5-turn circular coil of radius 5.15 cm can be oriented in any direction in a uniform magnetic field having a magnitude of 0.490 T. If the coil carries a current of 22.9 mA, find the magnitude of the maximum possible torque exerted on the coil. _______N*m?
*Friday, March 20, 2015 at 2:24pm*

**physics**

A 20.0 kg box slides down a 12.0 m long incline at an angle of 3.0 degrees with the horizontal. A force of 50.0 N is applied to the box to try to pull it up the incline. The applied force makes an angle of 0.00 degrees to the incline. If the incline has a coefficient of ...
*Friday, March 20, 2015 at 11:09am*

**Physics**

Consider holding a carton of milk in your hand. The force of the bicep muscle actsat an angle of 15 degrees to the vertical, while the weight of the arm and the milk both act downwards. The distance from the elbow to where the bicep muscle is attached via the distal bicep ...
*Thursday, March 19, 2015 at 10:25pm*

**Physics**

In 2286, Admiral Kirk and his crew were forced to use the slingshot effect in a stolen Klingon Bird-of-Prey to travel back in time to the late 20th century to retrieve two humpback whales. The stolen Klingon Bird-of-Prey traveled towards the sun at a velocity of vs while the ...
*Thursday, March 19, 2015 at 10:15pm*

**ap physics**

A student rides his bicycle at a constant speed of 2.20 m/s along a straight, level road. If the bike's tires each have a radius of 0.338 m, determine the following. (a) What is the tires' angular speed? rad/s (b) What is the net torque on each tire? N · m
*Thursday, March 19, 2015 at 10:02pm*

**ap physics**

A mass of 1.50 kg is at (−2.55 m, 0) and a 2.04-kg mass at (4.00 m, 4.00 m). Find the center of mass of the system. m, m
*Thursday, March 19, 2015 at 10:02pm*

**ap physics**

A man opens a 1.14-m wide door by pushing on it with a force of 49.5 N directed perpendicular to its surface. (a) What magnitude torque does he apply about an axis through the hinges if the force is applied at the center of the door? N · m (b) What magnitude torque does...
*Thursday, March 19, 2015 at 10:01pm*

**physics**

A bicycle tire has a mass of 2.54 kg and a radius of 0.346 m. (a) Treating the tire as a hoop, what is its moment of inertia about an axis passing through the hub at its center? kg · m2 (b) What torque is required to produce an angular acceleration of 0.710 rad/s2? N &...
*Thursday, March 19, 2015 at 10:00pm*

**physics**

A bowling ball of mass 7.45 kg is rolling at 2.56 m/s along a level surface. (a) Calculate the ball's translational kinetic energy. J (b) Calculate the ball's rotational kinetic energy. J (c) Calculate the ball's total kinetic energy. J (d) How much work would have...
*Thursday, March 19, 2015 at 9:59pm*

**Help with physics!**

Hi! I need some help with some physics questions. 1. When two point charges are moved farther apart, what is true about their resulting electric and gravitational forces? a. both forces stay the same b. gravitational force stays the same but electric force increases c. ...
*Thursday, March 19, 2015 at 8:43pm*

**physics**

A model rocket blasts off from the ground, rising straight upward with a constant acceleration that has a magnitude of 88.6 m/s2 for 1.57 seconds, at which point its fuel abruptly runs out. Air resistance has no effect on its flight. What maximum altitude (above the ground) ...
*Thursday, March 19, 2015 at 8:37pm*

**physics**

the positive point charges + q are placed at three corners of a square , and a negative point charge -Q is placed at the fourth , corner. the side of the square is L. calculate the net electric force that positive charges exert on the negative charge
*Thursday, March 19, 2015 at 7:56pm*

**physics**

Unpolarized light from an incandescent lamp has an intensity 112.0 Cd as measured by a light meter. a) What is in Cd the intensity reading on the meter when a single ideal polarizer is inserted between the bulb and the meter? b) What is in Cd the intensity reading on the meter...
*Thursday, March 19, 2015 at 7:46pm*

**physics**

In an historical movie, two knights on horseback start from rest 79.0 m apart and ride directly toward each other to do battle. Sir George's acceleration has a magnitude of 0.319 m/s2, while Sir Alfred's has a magnitude of 0.391 m/s2. Relative to Sir George's ...
*Thursday, March 19, 2015 at 7:22pm*

**Physics**

For the normal force exerted on the book by the wedge in the diagram, which force(s) complete(s) the force pair for Newton’s third law (action-reaction)? 1) the sum of the component of gravity perpendicular to the surface of the incline and the component of Fhand ...
*Thursday, March 19, 2015 at 7:20pm*

**Science, Physics**

Concave mirrors can be used as for shaving or applying make up. The face must be inside the focus. You hold a concave mirror, with a focal length of 40 cm, about 30 cm from your face. Where is your image located? How much bigger than your face is the image?
*Thursday, March 19, 2015 at 6:16pm*

**Physics**

A 1kg block of wood is moving with a velocity of 10 m/s on top of a table. The coefficient of kinetic friction between the block of wood and the table is 0.1. The block of wood is a cube with sides of 12 cm. How far does the block move before coming to a stop? If momentum is ...
*Thursday, March 19, 2015 at 6:04pm*

**Question**

Are there any physics teachers on this site that can help? I've posted many questions on here but none of them get answered.
*Thursday, March 19, 2015 at 5:53pm*

**physics**

a golfer hits a golf ball an initial velocity of 54m/s [42 degrees above the horizontal]. the ball lands on an elevated green that is 14m higher that the level from which the golfer hit the ball. a) how far away horizontally from the golfer does the ball land? b) what is the ...
*Thursday, March 19, 2015 at 2:59pm*

**physics**

A snowboarder is trying to gap a 14m wide road. He leaves the 19m high cliff at 10m/s at 30 degrees. Questions: 1. Does he make it? 2.When the snowboarder is 16m above the road, what is his speed?
*Thursday, March 19, 2015 at 2:15pm*

**physics**

A golfer is attempting to hit the ball onto an 18m green over a gorge. The location where the ball is hit from is elevated 35m above the green which is 65m away. Assume the ball was hit at a velocity of 20m/s at 40 degrees: Questions: 1. does the ball land on the green and why...
*Thursday, March 19, 2015 at 2:14pm*

**physics**

if an iron cube of volume 400cm3 is immersed in water,the upthrust will be?
*Thursday, March 19, 2015 at 11:28am*

**physics**

calculate the average angular acceleration and initial angular velocity of a wheel that has w=1.5wo(initial omega) at the end of 1min and w=45rev/sec at the end of 3min
*Thursday, March 19, 2015 at 9:12am*

**physics**

. A copper wire 1.00 mm in diameter is used to support a mass of 6.0 kg. If the wire was stretched by 2.00 mm, what was the original length of the wire? Y = stress/ strain r= 0.5 mm =5 X 10-4 m e= 2mm or 2 X 10-3 Given : m = 6 kg F = 60 N A =π r2 = ( 3.14)( 5 X 10-4) (5 X...
*Thursday, March 19, 2015 at 4:23am*

**physics**

A 50 kg girl runs up the stairs to a floor 6m higher in 10 s. What is her power output? P=f.dt P=(50kg x 10m/s2 x6m) __________________ 10 = 300J/s or 300 watts
*Thursday, March 19, 2015 at 4:14am*

**physics**

An electron has an initial velocity of 2.00 ✕ 10 6 m/s in a uniform 6.00 ✕ 10 5 N/C strength electric field. The field accelerates the electron in the direction opposite to its initial velocity. (a) What is the direction of the electric field? (b) How far does ...
*Thursday, March 19, 2015 at 2:27am*

**Physics **

Three collinear charges +7.0 x10^-5 C , +4.8 x10*-5 C, and -8.0 x 10^-5 C exert forces on each other. The first and second charges are 35.0 cm apart. The second and third charges are 35.0 cm apart. What is the magnitude and charge of the total force on the third charge? I know...
*Thursday, March 19, 2015 at 12:13am*

**physics help **

Please explain the answers. Thank You 1. A rifle is fired horizontally over a large flat plane. At the instant the rifle is fired, a student drops a second identical bullet from the same height as the rifle. Which bullet hits the ground first? 2. A monkey is hanging from a ...
*Thursday, March 19, 2015 at 12:06am*

**physics**

a golfer hits a golf ball an initial velocity of 54m/s [42 degrees above the horizontal]. the ball lands on an elevated green that is 14m higher that the level from which the golfer hit the ball. a) how far away horizontally from the golfer does the ball land? b) what is the ...
*Thursday, March 19, 2015 at 12:01am*

**Physics**

A 1,280-kg car pulls a 350-kg trailer. The car exerts a horizontal force of 3,600-N against the ground in order to accelerate. What force does the car exert on the trailer? Assume an effective friction coefficient of 0.15 for the trailer.
*Wednesday, March 18, 2015 at 9:22pm*

**Physics**

A projectile is launched from a compressed spring on an inclined plane. The spring constant of the spring is k= 10 N/m, the mass is 1kg and the plane is inclined 30 degrees to the horizontal. If the spring is compressed 15 cm what will be the velocity of the projectile when it...
*Wednesday, March 18, 2015 at 9:11pm*

**physics**

A 1100-kg car moving on a horizontal surface has speed v = 60km/h when it strikes a horizontal coiled spring and is brought to rest in a distance of 3.1m .What is the spring stiffness constant of the spring?
*Wednesday, March 18, 2015 at 8:45pm*

**physics**

Help: A 2 meter long, uniform bar with a mass of 46 kg is suspended from a pin so it can rotate freely. It is supported by a cable half a meter from the end. Find the tension force in the cable and the magnitude and direction of the reaction force at the wall for the bar to move
*Wednesday, March 18, 2015 at 7:42pm*

**physics**

A tourist being chased by an angry bear is running in a straight line toward his car at a speed of 5.04 m/s. The car is a distance d away. The bear is 17.5 m behind the tourist and running at 7.26 m/s. The tourist reaches the car safely. What is the maximum possible value for d?
*Wednesday, March 18, 2015 at 7:15pm*

**physics**

A student pushes a coin off the edge of a counter with some horizontal velocity. At the instant the coin goes over the edge, a second student drops a second coin from countertop level so it falls vertically to the floor. Which coin hits the floor first? please help
*Wednesday, March 18, 2015 at 3:01pm*

**physics**

A taxi hurries for 1 hour 3 minutes wit a constant speed of 118km/hr and then for another 1 hour 9 minutes with a constant speed of 40km/hr. What is its average speed for the total trip?
*Wednesday, March 18, 2015 at 2:06pm*

**physics**

Suppose you want to negotiate a curve with a radius of 50 meters and a bank angle of 15. If the coefficient of friction between your tires and the pavement is 0.50, what is the maximum speed that you can safely use? (NB: friction acts down the slope).
*Wednesday, March 18, 2015 at 11:02am*

**Physics**

Hi guys, I'm a little stuck on this question I'm doing at the moment. If anyone has spare time, I'd be extremely grateful! A lens with 50-cm focal length produces a real image the same size as the object. a)How far from the lens is the object? b)How far from the ...
*Wednesday, March 18, 2015 at 10:53am*

**Physics**

Hello!I was wondering if anybody had the time to help me with this question. I am not sure what equation to use with three polarizing filters! I thought we use Malus' Law, but doesnt seem to work. Any help would be greatly appreciated!! The question: Unpolarized light ...
*Wednesday, March 18, 2015 at 10:41am*

**physics**

You have an RC circuit and you measure the "zero" voltage to actually be 2.385 [Volts]. The peak voltage is measured to be 8.262 [Volts]. At what voltage value will you look for t4 = time stamp for 15/16 total charge?
*Wednesday, March 18, 2015 at 9:55am*

**Physics**

Two systems are formed from a converging lens and a diverging lens, as shown in parts a and b of the drawing. (The point labeled "Fconverging" is the focal point of the converging lens.) An object is placed inside the focal point of lens 1 at a distance of 7.70 cm to...
*Wednesday, March 18, 2015 at 9:13am*

**Physics**

The near point of a naked eye is 32 cm. When an object is placed at the near point and viewed by the naked eye, it has an angular size of 0.068 rad. A magnifying glass has a focal length of 15 cm, and is held next to the eye. The enlarged image that is seen is located 63 cm ...
*Wednesday, March 18, 2015 at 9:11am*

**Physics**

The owner of a van installs a rear-window lens that has a focal length of -0.320 m. When the owner looks out through the lens at an object located directly behind the van, the object appears to be 0.240 m from the back of the van, and appears to be 0.330 m tall. (a) How far ...
*Wednesday, March 18, 2015 at 9:09am*

**physics**

A block of mass 3kg starts from rest and slides down a surface, which corresponds to a quarter of a circle of 1.6m radius. a) if the curved surface is smooth, calculate the speed of the block at the bottom. b) if the block 's speed at the bottom is 4m/s, what is the energy...
*Wednesday, March 18, 2015 at 7:48am*

**physics**

a =4.0 c point charge and a-4.0 point charge are placed as in figure .what is the potential difference va vb between two points
*Wednesday, March 18, 2015 at 7:06am*

**Physics**

A car, starting from rest, accelerates in the positive x direction. It has a mass of 1.10 x 103 kg and maintains an acceleration of 4.6 m/s^2 for 5 s. Assume that a single horizontal force accelerates the vehicle. Determine the power generated by this force.
*Wednesday, March 18, 2015 at 1:30am*

**Physics**

A 58 kg skier is coasting down a 250 slope. Near the top of the slope, her speed is 3.6 m/s. She accelerates down the slope because of the gravitational force, even though a kinetic frictional force of magnitude 71 N opposes her motion. Ignoring air resistance, determine the ...
*Wednesday, March 18, 2015 at 1:29am*

**Physics**

A 120 kg crate on the flatbed of a truck that is moving with an acceleration of 1.5 m/s^2 along the positive x axis. The crate does not slip with respect to the truck undergoes a displacement whose magnitude is 43 m. What is the total work done on the crate by all of the ...
*Wednesday, March 18, 2015 at 1:27am*

**Physics**

A weight lifter is bench-pressing a barbell whose weight is 710 N. He raises the barbell a distance of 0.65 m above his chest then he lowers it at 0.27 m. Determine the work done on the barbell by the weight lifter during:a.)the lifting phase and b.) the lowering phase.
*Wednesday, March 18, 2015 at 1:26am*

**Physics**

A solid sphere, a hoop, and a solid disk. all with equal masses and radii, roll at the same translational speed along a horizontal surface toward a ramp inclined at a 30 degree angle. Which of the three will make it furthest up the ramp before it stops and begins to roll back ...
*Wednesday, March 18, 2015 at 1:04am*

**Physics**

If the force of repulsion between two socks is .003 and they are 2 cm apart what is the charge on each sock
*Wednesday, March 18, 2015 at 12:01am*

**Physics**

How fast (in rpm) must a centrifuge rotate if a particle 8.55 cm from the axis of rotation is to experience an acceleration of 1000 g's? (use 9.8 m/s^2) You may assume constant angular velocity.
*Tuesday, March 17, 2015 at 9:38pm*

**Physics**

A 5.6 kg ball (I=2/3mr^2) starts on a hill 11.3 m above level surface of the ground. The ball then rolls (without slipping) down the hill. What is the linear speed of the ball when it reaches the bottom of the hill?
*Tuesday, March 17, 2015 at 9:34pm*

**Physics**

An ice skater with an initial moment of inertia of 1.44 kg*m^2 is spinning at a rate of 3 revolutions per second. As she extends her arm outward her moment of inertia increases to 2.52 kg*m^2. What is her new angular velocity (in rad/s)?
*Tuesday, March 17, 2015 at 9:33pm*

**physics**

M1 and M2 are two masses connected as shown. The pulley is light (massless) and frictionless. Find the mass M1, given that M2 (7.0 kg) accelerates downwards at 3.39 m/s2, θ is 30o, and μk is 0.45.
*Tuesday, March 17, 2015 at 7:21pm*

**physics**

A girl on top of a building drops a baseball from rest.at the same moment a boy below throws a golfball upwards towards her with a speed of 20m/s.the golfball is thrown from a point 18m below where the baseball is released.how far will the baseball have dropped when it passes ...
*Tuesday, March 17, 2015 at 5:43pm*

**physics**

A cat moving in a desert walks 15m due north, then 6m due east then south calculate the resultant of the cat.
*Tuesday, March 17, 2015 at 5:31pm*

**physics**

A dockworker loading crates on a ship finds that a 17-kg crate, initially at rest on a horizontal surface, requires a 70-N horizontal force to set it in motion. However, after the crate is in motion, a horizontal force of 53 N is required to keep it moving with a constant ...
*Tuesday, March 17, 2015 at 5:24pm*

**physics**

If the speed of sound in air is 340 m/s, what is. approximately the length of a shortest air column closed at one end that will respond to a tuning fork of frequency 134 Hz? Answer in units of cm.
*Tuesday, March 17, 2015 at 4:51pm*