PH 201 Recitation Homework Summer 2008

6/25, 6/26/08 Chapter 2

A parachutist bails out and freely falls 75.0 m. Her parachute then opens and she decelerates at 2.00 m/s² to a terminal speed. She falls the remaining 1200 m and hits the ground at 3.00 m/s. How long is she in the air? At what height does the fall begin?

6/30, 7/1/08 Chapter 3

A pilot wants to fly to a neighboring town that lies 195 km, 50.0 degrees N of W from his town. His plane can fly at 62.5 m/s (about 140 mph). However, there is a wind blowing straight south at 18 m/s. What must his heading be in order to fly to the neighboring town in a single straight line? How long will this flight take?

7/2, 7/3/08 Chapter 4

In physics lab, a 0.500-kg block slides at a constant speed up an inclined plane on the lab table. A string runs parallel to the inclined plane, up and over a massless, frictionless pulley where it is attached to a suspended, falling mass, m. If the angle of the ramp is 20.0 degrees from horizontal, the coefficient of kinetic friction between the block and ramp is 0.25, find mass m.

7/7, 7/8/08 Chapter 6

A 45.0 kg child climbs up a 5.00 m tall ladder (vertical height) to sit atop a 7.00 m long slide. If she pushes off at the top with an initial speed of 2.00 m/s and the coefficient of kinetic friction between her pants and the slide is 0.150, what is her speed as she reaches ground level after sliding down the slide? Use energy principles to find the answers. For some extra practice (final in a couple weeks), you may want to use Newton’s Second Law and kinematics equations to compare the techniques and results.

7/9, 7/10/08 Chapter 7

Even though it was after the 4^th of July, Fred and Ed are still playing with fireworks. They stick a firecracker into a lump of dirt and place it on the ground and light the fuse. They observer that when it explodes, it breaks the dirt clod into 3 pieces, all of which move off horizontally on the perfectly frictionless parking lot. The first piece, of mass m, heads due north at 25.0 m/s. The second piece, also of mass m, moves east at 30.0 m/s. The third piece has mass 2m. What is the velocity of this third piece?