Physics unit 4 newtons 3 laws
Terms in this set (75)
As a 500 N woman sits on the floor, the floor exerts a force of _____________ on her.
the same (equal)
An unfortunate bug splatters against the
windshield of a moving car. Compared to the force
of the car on the bug, the amount of force of the bug on the car is _______________.
An unfortunate bug splatters against the
windshield of a moving car. Compared to the
deceleration of the car, the deceleration of the bug is __________________.
mass times velocity
The momentum of an object is defined as the
impulse acting on it
The momentum change of an object is equal to
twice as much momentum
Compared to a sports car moving at
50miles/hour, the same sports car moving at 100
miles/hour has _____________________.
action and reaction
The motion of a jet aircraft is primarily based on
the law of __________________.
increase the time of impact in collision
The reason padded dashboards are used in cars is
that they ________________.
there is no net external force acting on the system
Momentum of a system is conserved only when ______________________.
the objects that collide don't get warmer, after the collision, the objects have the same shape as before the collision, and the objects don't stick together
A collision is considered elastic if ___________________.
The pull of the ball's mass on Earth
As a ball falls, the action force is the pull of Earth's mass on the ball. What is the reaction to this force?
the small car
A large truck 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 ______________________.
A force is exerted on the tires of a car to accelerate the car along the road. The force is exerted by the _____________________.
Your friend says that the heavyweight champion of the world cannot exert a force of 950 N on a piece of tissue paper with the best pinch. The tissue paper is in midair, no wall and no tricks. Do you agree or disagree with him?
it is accelerating (or decelerating ), there is a force acting on it, and its velocity is changing
If the momentum of an object changes and its mass remains constant, ____________________________.
A 2-kg ball is thrown at 5 m/s. What is the ball momentum?
A person is attracted toward the center of the earth by a 500 N gravitational force. The force of attraction of the earth toward the person is _________________________.
Which object has the greatest momentum?
a. a 700-gram bird flying at velocity of 15 m/s
b. a 1000-kilogram car traveling at 5 m/s
c. a 40-kilogram shopping cart rolling along at 1.5 m/s
d. a 300-kilogram roller coaster car traveling at 15 m/s
If two identical objects are moving at different velocities, the object that is moving faster will have ________________________.
A moving bus comes to a sudden stop and the passengers lurch forward. This is an example of ______________________.
it is accelerating (or decelerating, there is a force acting on it, and its velocity is changing
If the momentum of an object changes and its mass remains constant, _______________________.
increase the force acting on it, swing as hard as possible, and increase the time of contact with the ball
In order to increase the final momentum of a golf ball, we could _____________________.
A table tennis ball launcher is fired. Compared to the force on the ball, the force on the launcher is ________________________.
A freight train rolls along a track with considerable momentum. If it were to roll at the same speed but had twice as much mass, its momentum would be _______________________.
one half as large
A moving freight car runs into identical car at rest on the track. The cars couple together. Compared to the velocity of the first car before collision, the velocity of the combined cars after the collision is ______________________.
the exhaust gases
The force that accelerates a rocket into outer space is exerted on the rocket by _____________________.
Superman is at rest in space when he throws an asteroid that has more mass than he does. Which moves faster, Superman or the asteroid?
A 4 kg ball has a momentum of 132 kgm/s. What is the ball's speed?
A ball is moving at 4 m/s and has a momentum of 24 kgm/s. What is the ball's mass?
True or False: Momentum is defined as an object's mass times its acceleration.
True or False: Impulse is defined as the force exerted on an object times the time it lasts.
True or False: If a net force acts on a system, the system's momentum will change.
True or False: When two objects collide and stick together, the collision is said to be elastic.
True or False: If you are inside a car, you cannot push the car anywhere.
True or False: Momentum is a scalar quantity.
force over mass
acceleration equals ________________________.
If the change in momentum occurs over a short time, the force of _____________ is large.
Inertia in motion
Protect passengers from the effects of inertia
Newton's Second Law
F = m a
A mutual action between objects where each object exerts an equal and opposite force on each other.
Force equal and opposite to the action force
Newton's Third Law
To every action there is always an equal
Decrease the force of impact in a collision
The force exerted on an object multiplied by time during which the force acts
A collision in which the colliding objects become distorted and/or generate heat during collision
Law of Conservation of Momentum
In an absence of a net external force, the momentum of an object or system
of objects is unchanged
one half the product of its mass times its speed squared
Kinetic energy of an object is equal to ___________________.
increases by nine times
When car speed triples, its kinetic energy ______________________.
An object that has kinetic energy must be ___________________.
three times the work
Raising an auto in a service station requires work. Raising it three times as high requires ______________.
twice the KE
An empty truck traveling at 40 km/h has KE. How much KE does it have when it is loaded so its mass is twice but keeps the same speed?
Energy that is stored
no energy is lost
what happens to energy in energy transformation?
An object at rest may have ___________________.
A job is done slowly, and an identical job is done quickly. Both jobs require the same amount of work but different amounts of ____________________.
What is the work done in lifting 60 kg of blocks to a height of 2 m?
A 6 kg object moves at 2 m/s. Its kinetic energy is ___________________.
Work is force times _________________.
The amount of work done when a force of 300 N moves an object a distance of 2 m is _____________________.
divided by time
Power equals work ______________
A unit used to measure work is a ______________________-.
One Joule of work is the same as one _______________.
A unit of power is a __________________.
One horsepower is about the same as _________________________.
The amount of work done by two boys who each apply 400 N of force in an unsuccessful attempt to move s stalled car is __________________________.
Potential energy the energy of an object because of its __________________________.
Energy of motion is ____________________.
weight and height
Gravitational potential energy depends on __________________________.
True or False: The rate in which work is done is called energy.
True or False: A rock at the edge of a cliff has potential energy because of its position.
True or False: Energy transforms from one form to another with no net gain or loss.
True or False: Power and work are always equal.
True or False: When you do less work in a given time period, the power increases.
True or False: One watt is equivalent to one joule per meter.