Physical Exam 2
Two billiard balls having the same mass roll toward each other at the same speed. What is the net momentum of the two-ball system?
0 kg m/s
A ball is moving at 4 m/s and has a momentum of 48 kg∙m/s. What is the ball's mass?
12 kg
A 1000-kg car moving at 10 m/s that brakes to a stop in 5 s has an average braking force of
2000 N
A 4-kg ball has a momentum of 12 kg∙m/s. What is the ball's speed?
3 m/s
A 5000-kg freight car crashes into a 10,000-kg freight car at rest. They couple upon collision and move with a speed of 2 m/s. What was the initial speed of the 5000-kg freight car?
6 m/s
A 2-kg mass weighs 20 N and is held 4 m above the ground. Its potential energy relative to the ground is
80 J
The impulse-momentum relationship is a direct result of
Newton's second law
The conservation of momentum is closely related toǒ
Newton's third law
Whereas impulse involves the time that a force acts, work involves the
a distance that a force acts
Which of the following has the largest momentum relative to Earth?
a pickup truck speeding along a highway
When bullets are fired from an airplane in the forward direction of motion, the momentum of the airplane
decrease
A freight train rolls along a track with considerable momentum. If it rolls at the same speed but has twice as much mass, its momentum is
doubled
The force that accelerates a rocket in outer space is exerted on the rocket by the
exhaust gases
Padded dashboards in cars are safer in an accident than non-padded ones because an occupant hitting the dash has
increased time of contact and decreased contact force.
If a charging rhinoceros has momentum, it must also have
kinetic energy
An object may have potential energy because of its
location
When you are in the way of a fast-moving object and can't get escape, you will suffer a smaller force if the collision time is
long
A heavy truck and a small truck roll down a hill. Neglecting friction, at the bottom of the hill the heavy truck has greater
momentum
An object in motion will continue in motion with
momentum
A car traveling along the highway needs a certain amount of braking force to stop. More braking force is required when the car has
more mass , more momentum , less stopping distance
From the same height you simultaneously drop a lightweight tennis ball and a heavyweight bowling ball. When they hit the floor they have the same
speed
It is correct to say that impulse is equal to
the change in momentum
In order to catch a fast-moving softball with your bare hand, you extend your hand forward just before the catch and then let the ball ride backward with your hand. Doing this reduces the catching force because the
time of catch is increased
The distinction between impulse and force involves the
time the force acts
An object lifted 10 m gains a certain amount of potential energy. If it is lifted 20 m, its gain in potential energy is
twice as much
