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Physics Chapter 4
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Gravity
Terms in this set (66)
The total amount of kinetic and potential energy in a system
Mechanical energy
Stored energy
Potential energy
Transfer of energy through motion
Work
Energy in the form of motion
Kinetic energy
The ability to cause change
Energy
Energy may change from one form to another, but it cannot be created or destroyed under ordinary conditions
Laws of conservation of energy
The rate at which work is done
Power
The factor that has the greatest effect on kinetic energy
Velocity
Energy is measured in
Joule
Power is measured in
Watts
Work is measured in
Joules
A joule is measured in
Newton times meters
____ and _____ both involve transfer of energy
Work and heat
Energy transfer when a force acts over distance is
Work
Energy that flows from warmer to cooler materials is
Heat
A rock at the edge of a 200-m high cliffs has _____ potential energy than an equal sized rock at the edge of a 600-m high cliff
Less
The energy stored foods, fuels, and dry cells is
Potential energy
As a 500 N women sits on the floor, the floor exerts a force on her of
500 N
The momentum of an object is defined as the object's
Mass times velocity
The momentum change of an object is equal to the
Impulse acting on it
compared to a sport car moving at 50 miles/hour, the same sports car moving at 100 miles/hour has
twice as much momentum
The motion of a jet aircraft is primarily based on the law of
Action and reaction
The reason padded dashboards are used in cars in that they
increase the time of inspect in a collision
Momentum of a system is conserved only when
there is no net external force acting on the system
As a ball falls, the action force is pull of
the pull of the ball's mass on Earth
A large track and a small car traveling at the same speed have a head-on collision. The vehicle to undergo the greater change in velocity will be
the small car
A force exerted on the tires of a car to accelerate the car along the road. The force is exerted by the
road
Which of the following has largest momentum
A pickup truck traveling down the highway
A 2-kg ball is thrown at 5 m/s. What is the ball momentum?
10 kgm/2
A person is attracted toward center of the earth by a 500 N gravitation force. The force of attraction if the earth toward the person is
500 N/s
Which object has the greatest momentum?
a 100 kilogram car traveling at 5 m
If two identical objects are moving at different velocities, the object that is moving faster will have
greater momentum
A table tennis ball launcher is fired. Compared to the force on the ball, the force on the launcher is
the same
A moving freight car runs into identical car at rest on the track. Th cars couple together. Compared to the velocity of the first car before collision, the velocity of the combined cars after the collision is
one half as large
The force that accelerates a rocket into outer space is exerted on the rocket by
the exhaust gases
A 4 kg ball has a momentum of 132 kgm/s. What is the ball's speed?
33 m/s
A ball is moving at 4/ms and has a momentum of 24 kgm/s. What is the ball's mass.
6 kg
Momentum is defined as an object's mass times its acceleration
false
Impulse is defined as the force exerted on an object times the time it lasts
true
If a net force acts on system, the system's momentum will change
true
When two objects collide and stick together, the collision is said to be elastic
false
If you are inside a car, you cannot push the car anywhere
true
Momentum is a scalar quality
false
In physics, work is defined as
force times distance
Which of the following is a unit for work?
joule
Power is defined as the
work done on an object divided by the time
The unit of power is
watt
Which is NOT an example of work?
An elephant pushing against the wall
Potential energy is the energy of an object has because of its
location
Kinetic energy is directly related to
mass
Which has a greater kinetic energy, a car traveling at 30 km/h or a car half the mass traveling at 60 km/h
the 60 km/h car
Kinetic energy of an object is equal to
one half the product of its mass times speed squared
When car speed triples, its kinetic energy
increases by nine times
An object that has kinetic energy must be
moving
How many joules of work are done on a box when a force of 24N pushes it 3m
72 J
How much power is expected if you lift a 60 N crate 10 meters in 1 second
600 W
A 6 kg object moves at 2 m/s. It's kinetic energy is
12 J
Force x how long
impulse
Force x how far
work
we do work when we
List an object against Earth's gravity
The heavier the object or the higher we lift it
The more work we do
Work is done when
There is an application of force
Work is done when
There is movement of something by that force
Work is done against another force
Stretching a bow string, pushups, and friction
N
Meter
Power
Rate at which work is done
;