Physics11_Ch6_Momentum_PracticeProblems_ANSKEY

Physics11_Ch6_Momentum_PracticeProblems_ANSKEY
Physics 11
Chapter 6: Momentum
Practice Problems
Lesson 1: Momentum
1. A 1200kg car travels with a speed of 23m/s. What is the momentum of the
car? 2.76x104kg.m/s
2. A plane has a momentum of 4.5x105kg.m/s. If the plane’s mass is 2500kg,
determine how long it would take for this plane to travel from Vancouver to
Calgary (roughly 1000km). 1.54 hours.
3. A 45kg man walks at a brisk 3.5km/hr. W hat is the man’s momentum?
0.97m/s*45 = 43.75kg.m/s
Lesson 2: Impulse
4. An object is pushed with a force of 9.0 N for 0.30 s. What impulse is given to it?
3.0 kg?m/s
5. A 34.0 kg sled is accelerated by a constant force of 45.0 N from 2.00 m/s to
16.00 m/s.
(a) What impulse acted on the sled? 476 N?s
(b) For how long was the force acting on the wagon? 10.6 s
6. A chunk of ice with mass 12.0 kg slides along a frozen lake with a constant
velocity of 3.90 m/s. A constant force then acts on the block of ice for 6.50 s,
changing its velocity to 17.00 m/s.
(a) What is the momentum of the block of ice before and after the force acts?
Before: 46.8.0 kg?m/s; After: 204.0 kg?m/s
(b) Calculate the impulse on the ice block. Δp = 157.2kg?m/s
(c) What is the magnitude and direction of the force? The force is 24.2 N in
the same direction as the initial motion of the block.
7. A tennis ball may leave the racket on the serve with a velocity of 60.0 m/s. The ball’s
mass is 0.055 kg and it is in contact with the racket for 0.042 s. (a) What is the
impulse on the ball? the change in momentum is p final–p initial or 3.9 N?s –0 N?s =
3.3 N?s (b) What is the force on the ball? Use F = ?p/?t= 78.6 N
8. A 0.145 kg baseball pitched at 45.0 m/s is hit on a horizontal line drive straight back
toward the pitcher at 70.0 m/s. If the contact time between bat and ball is 0.0028 s,
calculate the impulse on the ball and the force between the ball and bat during contact.
Impulse: is 16.7 N?s; Force: 5955 N
9. What impulse produces a velocity change of 13.00 m/s in
a 48.5 kg mass? And
how long does this 5000N force act on the mass? Δp=p final–p initial= mΔv =
630.5 N?s: 0.13seconds.
Lesson 3: Collisions
10. A 8.5 kg brick is dropped onto a 6.5 kg toy truck, which
is moving across a level
floor at 0.50 m/s. With what velocity do the truck and brick continue to move, after the brick has landed on the truck? 0.22 m/s
11. A car of mass 1500 kg traveling at 17.0 m/s collides with the rear end of the car in
front of it, which has a mass of 750 kg and is traveling in the same direction at 10.5 m/s. If the 750kg car has a velocity of 15.3 m/s after the collision, what is larger car’s velocity after the collision? 14.6 m/s in the original direction
12. Two billiard balls, each of mass 450 g, roll towards each other: one with speed of
4.3 m/s and the other with a speed of 6.5 m/s. After the collision, the one that was
traveling faster reverses its direction and travels at 3.8 m/s. What is the velocity of the other ball? 6.0 m/s in the opposite direction
13. A ball of mass 1.2kg rolls along the ground at 12.1 m/s towards a 5.3 kg bowling
ball that is at rest. After the collision, the bowling ball travels at 0.75 m/s. What is the velocity of the child’s ball? 8.8 m/s
14. A sandbag is mounted on a cart that is at rest on a horizontal frictionless surface,
and their total mass is 4.5 kg. What will be the velocity of the cart and sandbag if
a bullet of mass 2.0 g is fired into the sandbag with a horizontal velocity of 500.
m/s? The p of the bullet is 1.0 N?s. This will be transferred to the sandbag etc (note that the bullet’s mass is too small to worry about in comparison to the other masses). The momentum
of the sandbag etc will now be 1.0 N?s, which gives it a velocity of 0.22 m/s.。