Homework #3 - University Physical Science (Bostwick)
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.
A hydraulic press properly arranged, like a simple lever, is capable of multiplying energy input.
false
When a cannon fires a cannonball at a given speed, the smaller recoil speed of the cannon is due to different
masses
If you push for an hour against a stationary wall, you do no work
on the wall
It is correct to say the impulse is equal to
the change in momentum
An object may have potential energy because of its
Location
When a simple machine multiplies force, it decreases
distance moved
A simple machine CANNOT multiply
energy
A heavy truck and a small car rolling down a hill at the same speed are forced to stop in the same amount of time. Compared with the force to stop the car, the force needed to stop the truck is
greater
A cannonball fired from a long-barrel cannon will have a greater muzzle velocity because the cannonball receives a greater
impulse
A bow is drawn so that it has 40 J of potential energy. When the arrow is fired its kinetic energy is ideally
less than 40 J.
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
Compared with falling on a wood floor, a wine glass may not break when it falls on a carpeted floor because of
longer time to stop
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
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
If you do work on an object in half the time, your power output is
twice
If you push an object twice as far while applying the same force, you do
twice as much work.
When you push an object a certain distance while applying twice the force, you do
twice as much work.
A moving object has
All of the above (energy, velocity, momentum, speed)