GT PHYSICS HOMEWORK: Chapter 6 – Momentum
Page 204
#4
When a force is exerted on an object, does a large force always produce a larger change in the object’s momentum than
a smaller force does? Explain?
No; because ∆p = F∆t, it is possible for a large force applied over a very short time interval to change the
momentum less than a smaller force applied over a longer time period.
#5
What is the relationship between impulse and momentum?
Impulse is equal to the change in momentum.
Page 211 #4 Two isolated objects have a head-on collision. For each of the following questions, explain your answer:
m1v1i + m2v2i = m1v1f + m2v2f
a) If you know the ∆p of one object, can you find the ∆p of the other object?
Yes, the momentum lost by one object must equal to the momentum gained by the other object.
b) If you know the v1i and v1f of one object and the mass of the other object (m2), do you have enough information
to find the v2f of the second object?
No, v2f also depends on v2i and m1
c) If you know the masses of both objects and the final velocities of both objects, do you have enough info to find
the initial velocities of both objects?
No, using the conservation of momentum, you could only find a relationship between v1i and v2i
d) If you know the masses and initial velocities of both objects and the final velocity of one object, do you have
enough info to find the final velocity of the other object?
Yes, using the conservation of momentum, you could substitute the given values and solve for vf
e) If you know the change in momentum of one object and the initial and final velocities of the other object, do
you have enough information to find the mass of either object?
No; You could find m1 if v1i and v1f are given, but you would need v2i and v2f to find m2
Page 220
#4
If two automobiles collide, they usually do not stick together. Does this mean the collision is elastic?
No, some KE is converted to sound energy and some is converted to internal elastic potential energy as
the cars deform, so the collision cannot be elastic.
#5
A rubber ball collides elastically with the sidewalk.
a) Does each object have the same kinetic energy after the collision as it had before the collision? Explain
No; if the collision is perfectly elastic, total KE is conserved, but each object can gain or lose KE
b) Does each object have the same momentum after the collision as it had before the collision? Explain
No; total momentum is conserved, but each object can gain or lose momentum