Thursday

December 18, 2014

December 18, 2014

**Recent Homework Questions About Physics**

Post a New Question | Current Questions

**Physics Collision problem**

A 238U nucleus is moving in the x-direction at 4.8×105m/s when it decays into an alpha particle (4He) and a 234Th nucleus. The alpha moves at 1.2×107m/s at 36∘ above the x-axis. a. Find the speed of the thorium nucleus. v= b. Find the direction of the motion ...
*Tuesday, November 25, 2014 at 11:24am*

**physics**

A 61.0 -kg bungee jumper is standing on a tall platform (h0 = 46.0 m), as indicated in the figure. The bungee cord has an unstrained length of L0 = 9.00 m, and when stretched, behaves like an ideal spring with a spring constant of 76.0 N/m. The jumper falls from rest, and it ...
*Tuesday, November 25, 2014 at 10:33am*

**physics**

a convertible travels down a straight, level road at a slow speed of 13 km/h. A person in the car throws a ball with a speed of 3.6 m/s forward at an angle of 30 degrees to the horizontal. Where is the car when the ball lands?
*Tuesday, November 25, 2014 at 8:32am*

**Physics**

I don't understand how to do this : A force of 40 N accelerates a 7.17 kg block at 6.0 m/s2 along a horizontal surface. Determine the normal.
*Tuesday, November 25, 2014 at 12:42am*

**Physics**

a 981 kg test car travels around a circular track with a radius of 0.625 km. if the magnitude of centripetal force is 2433, what is the cars speed? what is the cars centripetal acceleration?
*Tuesday, November 25, 2014 at 12:12am*

**Physics**

Car 1 going northward (direction 90 degrees) at 14 m/s in an SUV weighing 2300 kg. car 2 going southwest (direction 225 degrees) at 16 m/s in a car that weighs 1600 kg. it is a completely inelastic collision. What is the direction and speed of the two vehicles immediately ...
*Tuesday, November 25, 2014 at 12:00am*

**physics /astronomy**

If a system has multiple planets all in the exact same orbital plane, does the transit of one planet imply that all planets in the system must transit as well?
*Monday, November 24, 2014 at 9:28pm*

**physics**

A disk with mass m = 5.2 kg and radius R = 0.44 m hangs from a rope attached to the ceiling. The disk spins on its axis at a distance r = 1.59 m from the rope and at a frequency f = 18.6 rev/s (with a direction shown by the arrow). 1. What is the magnitude of the angular ...
*Monday, November 24, 2014 at 9:22pm*

**physics**

A ball player hits a home run, and the baseball just clears a wall 17.6 m high located 122.0 m from home plate. The ball is hit an an angle of 35° to the horizontal, and air resistance is negligible. Assume the ball is hit at a height of 1.1 m above the ground. (a) What is...
*Monday, November 24, 2014 at 9:18pm*

**physics**

Suppose that you have a masa os 45.7 kg and are standing on frictionless roller skates. Someone then throws you a 2.50 kg mass with a velocity of 14.5 m/s and you catch it. What will be your resultant velocity?
*Monday, November 24, 2014 at 9:04pm*

**now mr. damon, physics**

A 63.8 kg block of silver is at initially at 107 C. 1.0 kg of ice at its freezing point is placed onto the block to cool it. As the ice melts, the water is free to flow off (so that the water never increases in temperature). After all the ice melts, what is the final ...
*Monday, November 24, 2014 at 8:32pm*

**physics**

A 3.02 kg mass attached to a light string rotates on a horizontal, frictionless table. The radius of the circle is 1.2 m, and the string can support a mass of 33.8 kg before breaking. The acceleration of gravity is 9.8 m/s 2 . What maximum speed can the mass have before the ...
*Monday, November 24, 2014 at 8:32pm*

**physics (would mr. sue or mrs damen answer my ques**

A 63.8 kg block of silver is at initially at 107 C. 1.0 kg of ice at its freezing point is placed onto the block to cool it. As the ice melts, the water is free to flow off (so that the water never increases in temperature). After all the ice melts, what is the final ...
*Monday, November 24, 2014 at 8:20pm*

**physics, please help**

A 63.8 kg block of silver is at initially at 107 C. 1.0 kg of ice at its freezing point is placed onto the block to cool it. As the ice melts, the water is free to flow off (so that the water never increases in temperature). After all the ice melts, what is the final ...
*Monday, November 24, 2014 at 8:09pm*

**Physics**

A guitar string has a mass of 30g and length of 2m. Find the tension if its density is 0.2kg/m^3
*Monday, November 24, 2014 at 8:08pm*

**physics**

A 63.8 kg block of silver is at initially at 107 C. 1.0 kg of ice at its freezing point is placed onto the block to cool it. As the ice melts, the water is free to flow off (so that the water never increases in temperature). After all the ice melts, what is the final ...
*Monday, November 24, 2014 at 7:48pm*

**physics**

Two sounds have measured intensities of I1 = 102 W/m2 and I2 = 408.00 W/m2. By how many decibels is the level of sound 1 lower than that of sound 2? Answer in dB
*Monday, November 24, 2014 at 7:35pm*

**physics**

on the surface of planet y, which has a mass of 4.38 x10^24 kg, an object has a weight of 50.0 N and a mass of 30.0 kg. What is the radius of this planet?
*Monday, November 24, 2014 at 7:33pm*

**physics**

An airplane of mass 1.30 104 kg is moving at 52.0 m/s. The pilot then increases the engine's thrust to 7.00 104 N. The resistive force exerted by air on the airplane has a magnitude of 3.00 104 N.
*Monday, November 24, 2014 at 7:24pm*

**physics**

Elephants communicate via infrasound, at frequencies as low as 14 Hz that can travel up to 10 km. The intensity of these sounds can reach 103 dB, measured a distance of 5.0 m from the source. Determine the intensity level of the infrasound 10 km from the source, assuming the ...
*Monday, November 24, 2014 at 7:20pm*

**physics**

A thin rod (uniform density & thickness) has mass M and length L. It is attached to the floor at a fixed location by a friction-less hinge. The rod start at rest, balanced vertically on its hinge end. ______________________________________ 1) While balanced vertically, the ...
*Monday, November 24, 2014 at 6:54pm*

**physics**

Calculate the radius of a “super- Earth” with 10 times the mass of Earth, using Earth data as a starting point.
*Monday, November 24, 2014 at 6:28pm*

**Physics**

The speed of a transverse wave on a string is 18 m/s when the tension is 3.0 N. What tension is required for the wave speed along the string to be 19 m/s? Answer in Newtons.
*Monday, November 24, 2014 at 6:23pm*

**physics**

A harmonic wave is traveling along a string. If the oscillator that generates the wave completes 23 vibrations in 18.50 seconds and if it takes a crest 20.21 seconds to travel 168 cm along the rope. What is the wavelength of the wave? Answer in cm.
*Monday, November 24, 2014 at 6:06pm*

**chemistry physics**

A car is traveling toward you at 40.0 mi/h. The car horn produces a sound at a frequency of 480 Hz. What frequency do you hear? Assume that the sound velocity in air is 1090 ft/s. Do I need to convert ft/s to m/s?
*Monday, November 24, 2014 at 5:19pm*

**Chemistry Physics**

What frequency is heard by an observer who hears the 450 Hz siren on a police car traveling at 35 m/s away from her? Assume that the velocity of sound in air is 345 m/s. Is this the correct? 450*345/(345+35) =408Hz
*Monday, November 24, 2014 at 5:10pm*

**math physics**

What frequency is heard by an observer who hears the 450 Hz siren on a police car traveling at 35 m/s away from her? Assume that the velocity of sound in air is 345 m/s. Is this the correct? 450*345/(345+35) =408Hz
*Monday, November 24, 2014 at 5:04pm*

**Physics**

A 250kg box is pushed horizontally with a force of 750 Newtons. If the coefficient of friction is 0.25, calculate the net acceleration of the crate. I am confused how I am to find the net acceleration. I solved to find FN and FG is 2452 N is that correct
*Monday, November 24, 2014 at 4:48pm*

**physics**

Question: Object A is moving at a maximum speed of 6m/s towards Object B. At 50 m away Object B accelerates from the approaching Object A at 0.3m/s^2. Does Object A catch up to Object B and if yes when? I don't know how to answer this at all or even which kinematic ...
*Monday, November 24, 2014 at 4:11pm*

**Math Physics**

What is the wavelength in metres of an electromagnetic wave with a frequency of 10^14/s?
*Monday, November 24, 2014 at 3:14pm*

**physics**

A weightlifter has a basal metabolic rate of 64.6 W. As he is working out, his metabolic rate increases by about 650 W. (a) How many hours does it take him to work off a 450 Calorie bagel if he stays in bed all day? (b) How long does it take him if he's working out? (c) ...
*Monday, November 24, 2014 at 3:11pm*

**College Physics**

A weightlifter has a basal metabolic rate of 64.6 W. As he is working out, his metabolic rate increases by about 650 W. (a) How many hours does it take him to work off a 450 Calorie bagel if he stays in bed all day? (b) How long does it take him if he's working out? (c) ...
*Monday, November 24, 2014 at 3:09pm*

**College Physics**

(a) How many hours does it take him to work off a 450 Calorie bagel if he stays in bed all day? (b) How long does it take him if he's working out? 2 h (c) Calculate the amount of mechanical work necessary to lift a 126 kg barbell 2.10 m. 3 J (d) He drops the barbell to the...
*Monday, November 24, 2014 at 3:06pm*

**Chemistry Physics**

What is the wavelength in metres of an electromagnetic wave with a frequency of 10^14/s?
*Monday, November 24, 2014 at 2:23pm*

**Chemistry Physics**

What is the wavelength of an electromagnetic wave with frequency 50.0 MHz? Am I starting this problem like this? 3.00*10^8/50*10^6 =6*10^12
*Monday, November 24, 2014 at 2:00pm*

**Math Physics**

What is the wavelength of an electromagnetic wave with frequency 50.0 MHz? Am I starting this problem like this? 3.00*10^8/50*10^6 =6*10^12
*Monday, November 24, 2014 at 1:58pm*

**Physics**

A 4.40kg block hangs from a spring with spring constant 2160N/m . The block is pulled down 4.60cm from the equilibrium position and given an initial velocity of 1.40m/s back toward equilibrium. A) What is the frequency of the motion? B) What is the amplitude? C) What is the ...
*Monday, November 24, 2014 at 1:01pm*

**physics**

is it possible to a have a percentage difference of zero in physics
*Monday, November 24, 2014 at 11:45am*

**Physics**

In our physics class we launched a rocket up into the air. We measured the time it took to go up to the point it reached the ground once again. How do I find the maximum height the rocket reached?
*Monday, November 24, 2014 at 11:41am*

**physics **

we did a lab and my observation chart is like this when my mass is 1.4 kgs (height is 0.12m,distance is 1.0m,time is 0.87s,velocity is 1.1 m/s ,Eg is 1.6 and the Ek is 0.85) when my mass is 2.14 kgs(height is 0.12m,distance is 1.0m,time is 0.88s,velocity is 1.1 m/s ,Eg is 2.8 ...
*Monday, November 24, 2014 at 11:24am*

**physics**

If an atom has an electron in the n = 5 state with ml = 3, what are the possible values of l?
*Monday, November 24, 2014 at 10:30am*

**physics**

it takes about 560 kilowatts to run a diesel locomotive at speed around 180km/h.Magnetically levitated trains(mag levs) on the other hand require less power because the magnetic levitation eliminates energy loss to friction.The worst maglev system requires 270 watts to ...
*Monday, November 24, 2014 at 10:17am*

**physics**

Please Help!! How much power is developed by a jumbo jet that cruises at 250 m/s. When the trust of its engine is 100,000 N? Thanks!!!
*Monday, November 24, 2014 at 6:01am*

**physics**

How much power is developed by a jumbo jet that cruises at 250 m/s. When the trust of its engine is 100,000N?
*Monday, November 24, 2014 at 6:00am*

**Physics**

A ball is thrown horizontally with a velocity of 40 m/s from the top of a building. Find its velocity and displacement after 3 s.
*Monday, November 24, 2014 at 4:57am*

**physics**

calculate the number of kilocalories needed to climb 232 stair steps (116 steps per minute for 2 min.) climbing stairs (116/min.) = energy consumption rate is 9.8 (kcal/min)
*Monday, November 24, 2014 at 3:28am*

**physics**

calculate minimum effort required to move load of 39 Newton in inclined plane whose length of slope is 39m ,height is 5m, distance from the base is 12m?
*Monday, November 24, 2014 at 1:05am*

**physics**

A(n) 1949.1 kg car is coasting along a level road at 22.9 m/s. A constant braking force is applied, such that the car is stopped in a distance of 74.6 m. What is the magnitude of the braking force? Answer in units of N
*Sunday, November 23, 2014 at 11:53pm*

**physics**

A(n) 1949.1 kg car is coasting along a level road at 22.9 m/s. A constant braking force is applied, such that the car is stopped in a distance of 74.6 m. What is the magnitude of the braking force? Answer in units of N
*Sunday, November 23, 2014 at 11:52pm*

**physics**

A 4.40kg block hangs from a spring with spring constant 2160N/m . The block is pulled down 4.60cm from the equilibrium position and given an initial velocity of 1.40m/s back toward equilibrium. What is the frequency of motion? What is the amplitude? What is the total ...
*Sunday, November 23, 2014 at 11:08pm*

**physics**

A 0.500kg ball is tied to the end of a 1.50m string and revolved so its andle thata is 35 degrees. a.) find the velocity of the ball (ans 2.43)
*Sunday, November 23, 2014 at 10:13pm*

**physics**

A 1.2kg lead ball is launched off a cliff top at 16m/s at an angle of 20 degrees above the horizontal. The height of the horizontal is 15m. Determine the net force acting on the lead ball that caused the ball to drop 4.0m from point P.
*Sunday, November 23, 2014 at 9:54pm*

**Physics**

An 8.00g bullet is fired at 220m/s into a 250g wooden block that is initially at rest. The bullet remains in the block and after the collision the two slide up a 30 degree incline. a) Solve for the velocity of the bullet block after the collision. b) Determine the distance ...
*Sunday, November 23, 2014 at 9:36pm*

**Physics**

A lathe, initially at rest, accelerates at .60 rad/s^2 for 10s, then runs at a constant angular velocity for 20s, and finally decelerates uniformly for 10s to come to a complete stop. What is its average angular velocity?
*Sunday, November 23, 2014 at 9:24pm*

**Physics**

The angular velocity of a wheel is given by w(t) = (2.00 rad/s^2)t + (1.00 rad/s^4)t^3. A. What is the angular displacement of the wheel from time t=0.00s to time t=T? B.What is the angular acceleration of the wheel as a function of time?
*Sunday, November 23, 2014 at 9:22pm*

**College Physics**

A thin rod (uniform density & thickness) has mass M and length L. It is attached to the floor at a fixed location by a friction-less hinge. The rod start at rest, balanced vertically on its hinge end. ______________________________________ 1) While balanced vertically, the ...
*Sunday, November 23, 2014 at 9:18pm*

**physics please help **

On the surface of a planet an object is thrown vertically upward with an initial speed of 60 m/s. use a conservation of energy approach to determine the object's speed when the object is at a quarter of it's maximum height. (assume the planet has no atmosphere) PLEASE ...
*Sunday, November 23, 2014 at 8:53pm*

**physics please help **

a 65 kg bag is dragged along a 12m ramp in order to get from the ground to the floor of the loading dock 2m above the ground. determine the efficiency of of the ramp. The frictional force acting on the bag is 50N due to the ramp. I don't understand how to the find the ...
*Sunday, November 23, 2014 at 8:43pm*

**Physics**

A thin rod (uniform density & thickness) has mass M and length L. It is attached to the floor at a fixed location by a friction-less hinge. The rod start at rest, balanced vertically on its hinge end. ______________________________________ 1) While balanced vertically, the ...
*Sunday, November 23, 2014 at 8:21pm*

**physics **

When a wave crosses a boundary between a thin and a thick rope, its frequency changes, but its wavelength and speed do not. True or false I think the answer is True
*Sunday, November 23, 2014 at 7:48pm*

**physics**

An object of mass 1.5 kg rests on a shelf where it has a gravitational potential energy of 7 joules. An object of mass 4.5 kg is placed on the same shelf. What is the gravitational potential energy of this second object?
*Sunday, November 23, 2014 at 7:38pm*

**PLEASE HELP PHYSICS**

True or False 1. The frequency of the wave can be changed by changing the frequency at which the waves are generated 2. Two crests are out of phase with each other. A crest and a trough are in phase with eachother 3. When a wave reaches the boundary of a new medium, part of ...
*Sunday, November 23, 2014 at 7:37pm*

**Physics**

A roll of toilet paper (a partially hollow cylinder with R_2 = 7.5cm, M = 300g, and I = 9.0 x 10^-4 kg m^2) is mounted on a mass-less axle along its central axis. Te roll is initially at rest. Then, at t=0, a child grabs the end of the roll and starts running, pulling the ...
*Sunday, November 23, 2014 at 7:29pm*

**physics**

a 65 kg bag is dragged along a 12m ramp in order to get from the ground to the floor of the loading dock 2m above the ground. determine the efficiency of of the ramp. The frictional force acting on the bag is 50N due to the ramp. I don't understand how to the find the ...
*Sunday, November 23, 2014 at 7:19pm*

**Physics **

True or false Wavelength is the distance between two adjacent points on a wave that are in phase My work I think it is false
*Sunday, November 23, 2014 at 6:54pm*

**Probability**

You have a blind date with a physics major. From your social networking experience, you know that 10% of physics majors are immature, 50% are narcissistic, and 90% are boring. Assume that immaturity, narcissism, and boringness are independent events. Calculate the probability ...
*Sunday, November 23, 2014 at 6:47pm*

**Physics**

A 0.118 kg baseball traveling with a horizontal speed of 3.14 m/s is hit by a bat and then moves with a speed of 33.7 m/s in the opposite direction. What is the magnitude of the change in the ball's momentum?
*Sunday, November 23, 2014 at 6:40pm*

**physics**

a 65 kg bag is dragged along a 12m ramp in order to get from the ground to the floor of the loading dock 2m above the ground. determine the efficiency of of the ramp. I don't understand how to the find the energy output and input.
*Sunday, November 23, 2014 at 6:30pm*

**Physics**

a projectile is fired at such an angel from the horizontal that the vertical componet of its velocity is 49m/s. the horizontal componet of its velocity is 61 m/s. what is the initial velocity of the projectile?
*Sunday, November 23, 2014 at 5:35pm*

**physics**

A sled on ice moves in the ways described in the questions below. Friction is so small that it can be ignored. A person wearing spiked shoes standing on the ice can apply a force to the sled and push it along the ice.Which force would keep the sled moving toward the right and ...
*Sunday, November 23, 2014 at 5:24pm*

**Physics **

True or false 1. When a wave reaches the boundary of a new medium,part of the wave can be reflected and part of the wave can be transmitted into the new medium. 2. When a wave crosses a boundary between a thin and a thick rope its frequency changes, but its wavelength and ...
*Sunday, November 23, 2014 at 5:10pm*

**Physics **

The frequency of the wave can be changed by changing the frequency at which the waves are generated. True or false My work I think the answer is false
*Sunday, November 23, 2014 at 4:41pm*

**physics**

Air at 1 atm is inside a cylinder 17.9 cm in radius and 17.9 cm in length that sits on a table. The top of the cylinder is sealed with a movable piston. A 24.1-kg block is dropped onto the piston. a) From what height above the piston must the block be dropped to compress the ...
*Sunday, November 23, 2014 at 4:27pm*

**Physics**

A projectile of mass 0.99 kg is shot from a cannon. The end of the cannon’s barrel is at height 6.6 m, as shown in the figure. The initial velocity of the projectile is 9.2 m/s. The projectile rises to a maximum height of ∆y above the end of the cannon’s barrel...
*Sunday, November 23, 2014 at 4:09pm*

**physics**

A proton moves with a velocity V (2i - 4 j + k) m / s in a region where the field is given by B = (i + 2 j -3k) T . What is the magnitude of the magnetic force experienced by the load?
*Sunday, November 23, 2014 at 3:53pm*

**physics**

Moving fast proton of 4x106 m / s through a 1.7 T magnetic field experiences a force 8x10-13N magnetic. What is the angle between the velocity vector associated with the proton and the magnetic field?
*Sunday, November 23, 2014 at 3:48pm*

**Physics**

A 4.40kg block hangs from a spring with spring constant 2160N/m . The block is pulled down 4.60cm from the equilibrium position and given an initial velocity of 1.40m/s back toward equilibrium. What is the frequency of motion? What is the amplitude? What is the total ...
*Sunday, November 23, 2014 at 3:45pm*

**Physics**

A piece of aluminum has a volume of 1.55 x 10-3 m3. The coefficient of volume expansion for aluminum is = 69 x 10-6(C°)-1. The temperature of this object is raised from 25.9 to 406 oC. How much work is done by the expanding aluminum if the air pressure is 1.01 x 105 Pa?
*Sunday, November 23, 2014 at 2:47pm*

**Physics**

A pond is 12 metres across. The crests of two successive waves are 60.0 cm apart and they each move across the pond in 15 seconds. a)What is the velocity of the waves? b)What is the frequency of the waves? c)What is the period of the waves?
*Sunday, November 23, 2014 at 2:12pm*

**Physics**

An aircraft landing on an aircrafts carrier is brought to a complete stop from an initial of 215km/h in 2.7 seconds. What is its acceleration in m/s2?
*Sunday, November 23, 2014 at 1:57pm*

**physics. I waited over two days for response**

An 800kg police boat slows down uniformly from 50km/h (E) to 20km/h(E) as it enters a harbour. If the boat slows down over a 30m distance, what is the force of friction of the boat? (Hint: you will need to convert the velocities into m/s) please show your work.
*Sunday, November 23, 2014 at 1:54pm*

**physics help please!!!!!!!!!**

An 800kg police boat slows down uniformly from 50km/h (E) to 20km/h(E) as it enters a harbour. If the boat slows down over a 30m distance, what is the force of friction of the boat? (Hint: you will need to convert the velocities into m/s) please show your work.
*Sunday, November 23, 2014 at 1:50pm*

**Physics**

A boy wants to throw a ball into his friend’s window 16.0 m above. Assuming it just reaches the window, he throws the ball at 55.0° to the ground. At what velocity should he throw the ball?
*Sunday, November 23, 2014 at 1:46pm*

**Physics help. please**

An 800kg police boat slows down uniformly from 50km/h (E) to 20km/h(E) as it enters a harbour. If the boat slows down over a 30m distance, what is the force of friction of the boat? (Hint: you will need to convert the velocities into m/s) please show your work.
*Sunday, November 23, 2014 at 1:21pm*

**Physics help. pls**

An 800kg police boat slows down uniformly from 50km/h (E) to 20km/h(E) as it enters a harbour. If the boat slows down over a 30m distance, what is the force of friction of the boat? (Hint: you will need to convert the velocities into m/s) please show your work.
*Sunday, November 23, 2014 at 1:21pm*

**physics**

An 800kg police boat slows down uniformly from 50km/h (E) to 20km/h(E) as it enters a harbour. If the boat slows down over a 30m distance, what is the force of friction of the boat? (Hint: you will need to convert the velocities into m/s) please show your work.
*Sunday, November 23, 2014 at 1:06pm*

**physics**

it takes about 560 kilowatts to run a diesel locomotive at speed around 180km/h.Magnetically levitated trains(mag levs) on the other hand require less power because the magnetic levitation eliminates energy loss to friction.The worst maglev system requires 270 watts to ...
*Sunday, November 23, 2014 at 12:19pm*

**Physics**

In a running event, a sprinter does 4.1 ✕ 105 J of work and her internal energy decreases by 8.1 ✕ 105 J.
*Sunday, November 23, 2014 at 12:07pm*

**Physics **

A certain car has an acceleration of 2.4m/s2.Assume that its acceleration remains constant. Starting from rest,how long does the car require to reach a velocity of 90km/h? How far does it travel while reaching that velocity?
*Sunday, November 23, 2014 at 11:39am*

**Physics**

An aircraft landing on an aircrafts carrier is brought to a complete stop from an initial of 215km/h in 2.7 seconds. What is its acceleration in m/s2?
*Sunday, November 23, 2014 at 11:31am*

**Physics**

A car accelerates from rest to 90km/h in 10 seconds.What is its acceleration in m/s2?
*Sunday, November 23, 2014 at 11:28am*

**physics**

a concrete slab of mass 400 kg accelerates down a concrete slope inclined at 35 degrees. the coefficient of kinetic friction between the slab and slope is 0.60. determine the acceleration of the block
*Sunday, November 23, 2014 at 10:48am*

**physics**

A ball thrown vertically upwards from ground level hits the ground after 4 seconds.Calculate the maximum height it reached during its journey.
*Sunday, November 23, 2014 at 10:34am*

**Physics**

An 800kg police boat slows down uniformly from 50km/h (E) to 20km/h(E) as it enters a harbour. If the boat slows down over a 30m distance, what is the force of friction of the boat? (Hint: you will need to convert the velocities into m/s) please show your work.
*Sunday, November 23, 2014 at 12:48am*

**Physics**

What is the vector product of A=2i + 3j + 1k and B=1i - 3j - 2k?
*Sunday, November 23, 2014 at 12:31am*

**Physics**

A person pushes on a doorknob with a force of 5N. The direction of the force is at an angle of 20 degrees from the perpendicular to the surface of the door. The doorknob is located .800m from axis of the hinges of the door. The door begins to rotate with an angular ...
*Sunday, November 23, 2014 at 12:29am*

**Physics**

A two dimensional object placed in the xy plane has three forces acting on it: a force of 3N along the x axis acting at a point (3m, 4m); A force of 2N along the y axis acting at (-2, 5m); and a force of 5N in the negative x direction acting at (-2m, -3m). What is the net ...
*Sunday, November 23, 2014 at 12:23am*

**Physics**

A man is holding an 8.00kg vacuum cleaner at arm's length, a distance of .550m from his shoulder. What is the torque on the shoulder joint if the arm is held at 30degrees below the horizontal?
*Sunday, November 23, 2014 at 12:16am*

**physics**

In an effort to loosen the bolt on the wheel of a car, a man with a mass of 70kg steps on the end of a 50cm tire iron which is extending horizontally from the bolt. How much torque is he applying to the bolt?
*Sunday, November 23, 2014 at 12:12am*

**Physics**

A lathe, initially at rest, accelerates at .60 rad/s^2 for 10s, then runs at a constant angular velocity for 20s, and finally decelerates uniformly for 10s to come to a complete stop. What is its average angular velocity?
*Sunday, November 23, 2014 at 12:08am*

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