energy problems

1. Consider a brick dropped from a 15-m height. Find the following:

a. initial potential energy
b. kinetic energy immediately before hitting the ground
c. velocity immediately before impact with ground
d. velocity at a point half-way down

2. Consider a "loop the loop," in which a small mass is dropped from some height (H) and is free to slide frictionlessly until reaching a loop of radius r. (See picture on page 190, problem 8, for clarification).

What is the minimum height (H) so that the mass will "just make" the loop? Solve in terms of r (loop radius). [answer: H = 5r/2 (or 2.5r)

3. A large mass (m --> see, I told you it was large!) is moving at a speed v. It hits a friction-y surface (u) and slides to a halt. What is the distance that it will travel before completely stopping? (Solve for the distance in terms of relevant variables.)

Text problems worth a look, in this order (in case you are limited for time):

Chapter 8:

9 (watch units)
21
15
36* (tricky, but fun!)

Looking ahead