Question

1) A catcher catches a fastball going 95mi/hr and recoils 12cm while stopping the ball in 0.005s. (mass of the ball is 280gm). a) What was the magnitude and direction of the change in momentum of the ball?   b) What was the average force the ball exerts on the hand & glove?

2) A 50kg driver sits stopped at a traffic light. Another car rear-ends her and causes her to accelerate at 16m/s^2. It all occurs in 0.25s.   a) What is the impulse given to the driver? b) What is the average force exerted on the driver and what exerts the force?

3) A wheel spinning at 25 rev/s is slowed to a stop by a constant acceleration while turning 50rev. a) What is the magnitude of the constant acceleration? b) How long did it take to stop?

4) A 75kg painter stands on a 5.5m long uniform plank resting on a scaffold. If the plank's mass is 20kg , how close to the left end of the plank can he stand without tipping the plank? ( The scaffold supports are 2.5m apart, and the plank extends beyond the scafold supports, 1.5m on each end.)

5) If 4 meter sticks were stacked on a table with 10cm, 15cm, 30cm & 50cm respectively hanging past the edge of the table, would the top meterstick stay on the stack or fall off?       (yes or no), and why?

Answer 1