PH 201 Recitation
Homework Spring 2007
Chapter 2
A parachutist bails out and freely falls 50.0 m. The parachute opens and she decelerates at 2.00 m/s2. She hits the ground at 3.00 m/s. How long is she in the air? At what height does the fall begin?
Chapter 3
A person walks up a stalled 15.0-m-long escalator in 90.0 s. When standing on the same escalator, now moving, the person is carried up in 60.0 s. How much time would it take that person to walk up the moving escalator? Does the answer depend on the length of the escalator?
Chapter 4
A 100-kg crate is pushed at constant speed up a frictionless ramp inclined at an angle of 30.0 degrees with the horizontal by a horizontally applied force with no vertical component. Note that the force is not parallel to the ramp. What are the magnitudes of all of the forces acting on the crate?
Chapter 6
A stone with a weight of 5.29 N is launched vertically from ground level with an initial speed of 20.0 m/s and the force of air resistance on it is 0.265 N throughout its flight. What is the maximum height reached by the stone? What is its speed just before it hits the ground? Use energy principles to find the answers.
Chapter 7
A vessel, initially at rest, explodes into three pieces, all of which move in the horizontal plane. The first piece, of mass m, moves west at 30.0 m/s. The second piece, also of mass m, moves south at 30.0 m/s. The third piece has mass 3m. What is the velocity of the third piece?