SAT Mechanics B - Energy and Momentum

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1. Which of these expressions is the rate of change of momentum?
• A) Δp
• B) m/t
• C) Δm/t
• D) Δp/Δt
• E) p/t
2. One of Newtons laws of motion states that the rate of change of momentum is equal to
• A) Acceleration
• B) Force
• C) Mass
• D) Velocity
• E) Impulse
3. A firework rocket accelerates for the first few seconds and gains height above the ground. Which of the following best describes the energy changes taking place at this point?
• A) chemical and potential converted to kinetic
• B) kinetic converted to chemical and potential
• C) chemical converted to potential and kinetic
• D) potential converted to kinetic and chemical
• E) potential and kinetic converted to chemical
4. The graph shows the force required to stretch a steel cable. What work has been done stretching the cable by 12 cm?
• A) 240 J
• B) 120 J
• C) 2.4 J
• D) 2.0 J
• E) 1.2 J
5. Momentum is defined as ..
• A) the product of mass and velocity
• B) the force required to stop an 1kg object travelling at 1ms-1
• C) the speed of an object multiplied by the distance traveled
• D) the rate of change of force
• E) the rate of change of velocity

6. A small steel ball of mass m is fired at a solid wall at a speed v. It rebounds at a speed of v/2.

The total momentum change is

• A) 3mv/2
• B) mv/2
• C) 2mv
• D) 2mv/3
• E) mv
7. An inelastic collision is one in which..
• A) the final velocity is less than the impact velocity
• B) momentum is not conserved
• C) kinetic energy is not conserved
• D) the final average velocity is less than the initial average velocity
• E) the momentum is conserved but the kinetic energy increases
8. A 20g bullet hits a 40g stationary block of wood at 60 m/s and remains embedded in the wood. What is the final velocity of block and bullet?
• A) 40 m/s
• B) 30 m/s
• C) 25 m/s
• D) 20 m/s
• E) 10 m/s

9. A 0.2kg tennis ball is hit at 20 m/s. Which answer gives the correct values for momentum and kinetic energy?

 Momentum (kgm/s) k.e. (J) A. 40 40 B. 4 200 C. 40 80 D. 40 20 E. 4 40
10. Estimate the impulse on the tennis ball as it is struck using information from this graph.
• A) 16 Ns
• B) 16 kNs
• C) 32 Ns
• D) 32 kNs
• E) 160 Ns