Assignment:
1. Problem 1: Impulse and Momentum
You release a 3kg firecracker from rest. At t = 0.4s, the firecracker is moving downward with speed 4m/s. At this same instant, the firecracker begins to explode into two pieces with masses mtop = 1kg and mbottom = 2kg. At the end of the explosion (t = 0.8s), the top piece is moving upward with speed 4m/s.
(a) Draw a picture of the system as it is described.
(b) Determine the magnitude of the net force on the firecracker.
(c) Determine the magnitude and direction of the net impulse on the firecracker system during the explosion (i.e., over the interval from t = 0.4 s until t = 0.8 s).
(d) Use the impulse-momentum theorem to determine the magnitude and direction of the change in momentum of the firecracker system during the explosion.
(e) Sensemaking: Make a momentum vector diagram for the situation. (draw the before, during, and after vectors of momentum of the firecracker, don't forget your axes.)
(f) Sensemaking: Draw a momentum bar chart for the system.
(g) Determine the final momentum of the firecracker system.
2. Problem 2: Momentum in 2-D
A 5.50kg bowling ball moving at 9.00m/s collides with a 0.850kg bowling pin, which is scattered at an angle of 85? with respect to the initial direction of the bowling ball and with a speed of 15.0m/s.
(a) Draw a diagram for the system before and after collision.
(b) Calculate the final velocity (magnitude and direction) of the bowling ball.
Now assume another bowling pin was also hit. This pin also weighs 0.850kg but is scattered at an angle of -30? with respect to the initial direction of the bowling ball and with a speed of 20.0m/s.
(c) Draw a diagram for the system before and after collision.
(d) Calculate the final velocity (magnitude and direction) of the bowling ball.
Now assume the bowling pins are actually clay so they stick to the bowling ball. Their combined weight is 1.7kg.
(e) Draw a diagram for the system before and after collision.
(f) Calculate the final velocity (magnitude and direction) of the bowling ball and the clay.
(g) Sensemaking: Compare your three answers. Do they make sense with your intuition? Resolve any inconsistency's and/or explain why they make sense.