## November 27, 2012

### Chapter 6: Work and Energy

Practice Problems
 1
Just as a car tops a 38 meter high hill with a speed of 80 km/h it runs out of gas and coasts from there, without friction or drag. How high, to the nearest meter, will the car coast up the next hill?

 2
A pendulum has a mass of 3.6 kg, a length of 1.7 meters, and swings through a (half)arc of 29.4 degrees. What is its amplitude to the nearest centimeter?

 3
To the nearest tenth of a Joule, what is its maximum kinetic energy of the pendulum in problem 2?

 4
To the nearest tenth of a Joule, what is the total energy of the pendulum in problem 2?

 5
A 2 kg metal plate slides down a 13-meter high slope. At the bottom its speed is 9 m/s. To the nearest Joule, what was the magnitude of the work done by friction?

 6
If the slope in the above problem is 23 degrees, what is the coefficent of friction (to 2 decimal places)?

 7
An unstretched spring with spring constant 36 N/cm is suspended from the ceiling. A 3.6 kg mass is attached to the spring and let fall. To the nearest tenth of a centimeter, how far does it stretch the spring?

 8
If the mass in the previous problem is attached to the spring and slowly let down, to the nearest tenth of a centimeter, how far does it stretch the spring?

 9
A mass of 2.2 kg is dropped from a height of 4.7 meters above a vertical spring anchored at its lower end to the floor. If the spring constant is 33 N/cm, how far, to the nearest tenth of a cm, is the spring compressed?

 10
If the top of the spring in the preceding problem is 1.34 meters above the ground when the mass is released, what is the ball's kinetic energy, to the nearest Joule, just before the mass strikes the spring?

Problem 1  The correct answer is 63.
Problem 2  The correct answer is 87.
Problem 3 The correct answer is 7.7.
Problem 4  The correct answer is 7.7.
Problem 5  The correct answer is 174.
Problem 6  The correct answer is 0.29.
Problem 7  The correct answer is 2.
Problem 8  The correct answer is 1.
Problem 9  The correct answer is 25.4.
Problem 10  The correct answer is 101.