Which undergoes the greatest change in momentum (if all of the baseballs have the same speed just before being caught and just after being thrown)?In the preceding question, which case requires the greatest impulse?
  • The speed of car B is equal to the initial speed of A.
  • For both questions:A baseball that is caught and then thrown back
  • Long contact time decreases the magnitude of the average force and is favorable.
  • Momentum is conserved in elastic and inelastic collisions.
Distinguish between force and impulse.
  • increasing the force or increasing the time interval.
  • It means momentum does not change.
  • Impulse is force times a time interval.
  • The average force is increased.
Can you produce a net impulse on an automobile if you sit inside and push on the dashboard?
  • Yes, always.
  • No, never.
  • 1.41 kg·m/s before and after.
  • The average force is increased.
If the equally massive cars of the preceding question stick together after colliding inelastically, how does their speed after the collision compare with the initial speed of car A?
  • Their speed is half the initial speed of car A.
  • The force is applied for a longer time in the long cannon.
  • 1.41 kg·m/s before and after.
  • The speed of car B is equal to the initial speed of A.
Which has a greater momentum: a heavy truck at rest or a moving skateboard?
  • It means momentum does not change.
  • The average force is increased.
  • F=ma=mΔv/Δt, so Ft=Δ(mv)
  • The moving skateboard.
In the preceding question, what is the total momentum of the balls of putty before and after the collision?
  • The force is applied for a longer time in the long cannon.
  • 1.41 kg·m/s before and after.
  • The average force is increased.
  • 1.41 kg·m/s
How is the impulse -momentum relationship related to Newton's second law?
  • The moving skateboard.
  • 1.41 kg·m/s before and after.
  • The average force is increased.
  • F=ma=mΔv/Δt, so Ft=Δ(mv)
Is it correct to say that, if no net impulse is exerted on a system, then no change in the momentum of the system will occur?
  • No, never.
  • Yes, always.
  • 1.41 kg·m/s
  • 1.41 kg·m/s before and after.
When you are struck by a moving object, is it favorable that the object makes contact with you over a short time or over a long time?
  • For both questions:A baseball that is caught and then thrown back
  • Rolling with the punch increases contact time, which decreases the force.
  • Long contact time decreases the magnitude of the average force and is favorable.
  • the momentum of the cannon is equal to the magnitude of the momentum of the cannon ball and points in the opposite direction.
Why is it advantageous to roll with the punch in boxing?
  • It means momentum does not change.
  • Long contact time decreases the magnitude of the average force and is favorable.
  • increasing the force or increasing the time interval.
  • Rolling with the punch increases contact time, which decreases the force.
An impulse can be increased by
  • increasing the force or increasing the time interval.
  • Rolling with the punch increases contact time, which decreases the force.
  • Impulse is force times a time interval.
  • exert the greatest force over the longest time.
When a cannonball is fired, the momentum of the system (cannon + cannonball) is conserved if...?
  • Momentum is conserved in elastic and inelastic collisions.
  • the momentum of the cannon is equal to the magnitude of the momentum of the cannon ball and points in the opposite direction.
  • Long contact time decreases the magnitude of the average force and is favorable.
  • The force is applied for a longer time in the long cannon.
Why is a force that is applied for a short time more effective in karate?
  • F=ma=mΔv/Δt, so Ft=Δ(mv)
  • The average force is increased.
  • It means momentum does not change.
  • The moving skateboard.
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