Practice Problems
Conservation of Momentum
Directions:
On this worksheet you will be practicing your knowledge of conservation of momentum.
Question 1
A 2.5-kg ball has a KE of 61.2 J. What is the ball's momentum?
122.5 kg m/sec
omit
8.8 kg m/sec
17.5 kg m/sec
15.7 kg m/sec
Question 2
A 45-kilogram skater at rest on a frictionless rink throws a 2.5-kilogram ball, giving the ball a velocity of 7 m/s. Which value describes the skater's subsequent motion?
-16.07 m/sec
-0.39 m/sec
-2.52 m/sec
omit
-0.06 m/sec
Question 3
A 6550-kg freight car moving at 7 m/sec collides and couples with an 16375-kg freight car which is initially at rest. The approximate common final speed of these two cars is
24.5 m/sec
2.8 m/sec
9.8 m/sec
5 m/sec
omit
2 m/sec
Question 4
A 4.5-g bullet moving at 308 m/sec is brought to a stop in 0.7 seconds when it strikes a tree. The average braking force exerted on the bullet by the tree is
-1.98 N
omit
-880 N
there is not enough information to calculate the force
-0.97 N
Question 5
You push two objects, both initially at rest, with the same amount of force through the same distance. Object A has mass,
m
, while object B has mass,
16m
.
B will gain 4 times as much KE as A
omit
A will gain 4 times as much KE as B
A will gain 4 times as much momentum as B
B will gain 4 times as much momentum as A
Question 6
A heavy and a light object are released from the same height and fall to the ground. Just before they strike the ground, they will have
gained the same kinetic energy
gained the same amount of momentum
omit
experienced the same force
none of the other choices are true
Question 7
A girl jumps upward from the surface of the earth.
Does an external force act on system 'girl + earth'?
omit
yes, because each participant (girl and earth) will experience a change in its momentum
no, the each participant (girl and earth) experience equal but opposite impulses and equivalent changes in momentum
yes, because each participant (girl and earth) will accelerate
no, all forces in the diagram cancel each other and neither participant (girl and earth) is accelerated
Question 8
Running at 3.5 m/sec Jack, a 45-kg quarterback, collides with Leon, a 90-kg tackle, who is traveling towards him at 7 m/sec. Upon colliding, Leon continues to travel forward towards Jack, at 1.4 m/sec. How fast does Jack leave the collision?
14.7 m/sec
omit
-2.8 m/sec
-7.7 m/sec
1.4 m/sec
Question 9
In which picture does Bronco have the greatest terminal velocity?
omit
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