Question 1 Multiple Choice
Which has more momentum: a 2,000 kg truck moving at 2 m/s or a 0.01 kg bullet moving at 500 m/s?
AThe truck (4,000 kg·m/s)
BThe bullet (5 kg·m/s)
CThey have the same momentum
DNeither has momentum because they are different objects
Truck momentum = 2,000 × 2 = 4,000 kg·m/s. Bullet momentum = 0.01 × 500 = 5 kg·m/s. The truck has far more momentum.
Question 2 True / False
A moving object's momentum doubles if its velocity doubles.
Answer: True
Since p = mv, and mass stays the same, doubling v doubles p. Momentum is directly proportional to velocity.
Question 3 Short Answer
A 50 kg skater moves at 3 m/s. What is her momentum?
Think about your answer, then reveal below.
Model answer: 150 kg·m/s, because p = mv = 50 × 3 = 150.
Momentum equals mass times velocity. 50 kg × 3 m/s = 150 kg·m/s in the direction she is moving.