# Physics 1: Work and Energy

A 20 kg student is about to go down a slide. There is a 3 N frictional force opposing his movement. Assume his velocity at the top of the slide is 0 m/s. Find his velocity at the bottom of the slide.

A marble, m, of mass 100 g is placed onto a platform attached to a spring. The weight of the marble compresses the spring 2 cm, as shown below. A force is then applied to the platform to compress the spring an additional 3 cm. When the force is taken away, the spring decompresses and launches the marble upward. What is the maximum height the marble obtains above the unstretched spring (the spring with no mass on it).

In an experiment to determine the spring constant of an elastic cord of length 0.60 m, a student hangs the cord from a rod and then attaches a variety of weights to the cord. For each weight, the student allows the weight to hang in equilibrium and then measures the entire length of the cord. The data are recorded in the table below:

iii. Calculate the maximum speed of the object.

A small sphere is moving at a constant speed in a vertical circle. Which of the following quantities is changing?

i. kinetic energy ii. potential energy iii. momentum

i and ii only

i and iii only

i and ii only

ii only

iii only

ii and iii only

In the situation above, after block 1 comes to rest, the force exerted on the rope must be equal in magnitude to

A. Zero

B. the frictional force on block 1

C. the vector sum of the force on block 1 due to the friction and tension in the spring

D. the sum of the weights of the two blocks

E. Shiang doesn't care, he just wants to sleep

F. the difference in the weights of the two blocks

A solid brass block of mass m slides along a frictionless track when released from rest along the straight section. The circular loop has a radius R.

B. Assume the block is released at height h = 6.0 R, what are the magnitude and direction of the horizontal force competent acting on the block at point Q?