# WS Impulse – Momentum Theory ```WS Impulse – Momentum Theory
Honors Physics
Complete the following on a separate piece of paper using methods demonstrated in class. BE SURE TO
SHOW ALL WORK &amp; USE THE METHOD FOR SOLVING WORD PROBLEMS IN ORDER TO
1. A 21 kg child on a 5.9 kg bike is riding with a velocity of 4.5 m/s to the northwest.
a) What is the total momentum of the child and the bike together?
Solution: 1.2 x 102 kg m/s [NW]
b) What is the momentum of the child?
Solution: 9.4 x 101 kg m/s [NW]
2. A truck loaded with sand is moving down a highway in a straight path. Explain (in 2 to 3 sentences) the two
ways in which the truck’s momentum could decrease.
3. While being thrown, a net force of 132 N acts on a 1.297 N baseball for a period of 4.51 x 10-2 seconds.
a) What is the magnitude of the change in momentum of the ball?
Solution: 5.95 kg m/s
b) If the initial speed of the baseball was 0 m/s, what will its speed be the moment it leaves the pitcher’s
hand?
Solution: 4.50 x 101 m/s
c) When the batter hits the ball (assuming it is the same speed as when it left the pitcher’s hand), a net force
of 1120 N, opposite the direction of the ball’s initial motion, acts on the ball for 9.57 x 10-3 seconds
during the hit. What is the final velocity of the ball just after it leaves the bat?
Solution: 3.6 x 101 m/s [toward the pitcher]
d) What force does the ball exert on the bat?
Solution: - 1.12 x 103 N
4. A 2.5 kg ball strikes a wall with a velocity of 8.5 m/s to the left. The ball bounces off with a velocity of 7.5
m/s to the right. If the ball is in contact with the wall for 0.25 s, what is the constant force exerted on the ball
by the wall.
Solution: 1.6 x 102 N [R]
5. A moving object has a kinetic energy of 150 J and a momentum with a magnitude of 30.0 kg m/s. Determine
the mass and the speed of the object.
Solution: m = 3. 0 kg and v = 1.0 x 101 m/s
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