physics unit2
Pressure is defined as
force per area
Accelerations are produced by
forces
Forces always occur
in pairs
Concider the gravitational force between earth and a meteor in outer space. If the meteor moves so its distance from the Earth's center doubles, the gravitational force on the meteor will be
one quarter
A book weighs 4 N, when held at rest in your hands, the net force on the book is
0N
Two people pull on a rope in a tug of war, each pulls with 400 n force. what is the tension in the rope?
400 N
as a care package falls froma high flying stationary helicopter, its velocity increases and its acceleration
Decreases
Newton had the insight to see that the
Force on the moon has the same nature as the force on an apple
gravitational forces are the weakest forces found in nature, because of this
Gravitational forces that are easily observed involve one or more larger masses
An object following a straight line path at constant speed
Has no forces acting on it.
If the mass of the earth increased with no change in the radius your weight would be
Increased
two objects move toward eachother because of gravitational attraction. As the objects get closer and closer, the force between them
Increases
Object A has twice as much mass as object B. This means object A also has twice as much
Inertia
If the force acting on a cart doubles, what happens to the cart's acceleration
It halves
Suppose a cart is being moved by a force. if suddenly a load is dumped onto the cart so that the cart's mass doubles, what happens to the cart's acceleration?
It halves
If the force of gravity suddenly stopped acting on the planets, they would?
Move in straight lines tangent to their orbits
Which has more mass, a kilogram of feathers or a kilogram of iron?
Neither-they both have the same mass
a rocket is able to accelerate in the vacuum of space when it fires its engines. the force that propels the rocket is the force
Of the exhaust gases on the rocket
the force of gravity on you is greatest when you are standing
On earths surface
A player catches a ball. Consider the action force to be the impact of the ball against player's glove. What is the reaction to this force?
The force the gloves exert on the ball
A heavy person and a light person parachute together and wear the same size parachutes. Assuming they open their parachutes at the same time, which person reaches the ground first?
The heavy person
An object weighs 30 N on earth, a second object weighs 30 N on the moon, which has greater mass?
The one on the moon
as a ball falls, the action force is the pull of earths mass on the ball. what is the reaction to this force
The pull of the balls mass on earth
why did newton think there was a force acting on the moon
because the moon moves in a curved path
Bronco the skydiver falls toward earth. the attraction of earth on bronco pulls him down. The reaction to this force is
bronco pulling up on earth
A tow truck exerts a force of 2000 N on a car, accelerating it at 1 m/s2. what is the mass of the car?
2000 kg
A 5-N force and a 30-N force act in the same direction on an object. What is the net force on the object?
35 N
an apple weighs 1 N. The net force on the apple when it is in freefall is
1 N
a 20 N falling object encounters 4 N of air resistence. The magnitude of the net force on the object is
16 N
a 10-kg brick and a 1-kg book are dropped in a vacuum. The force of gravity on the 10-kg brick is
10 times as much as the force on the 1-kg book
a karate chop delivers a blow of 2300 N to a board that breaks. The force that acts on the hand during this feat
2300 N
suppose the force of friction on a sliding object is 25 N. The force needed to maintain a constant velocity is
25 N
A girl whose weight is 500 N hangs from the middle of a bar supported by two vertical strands of rope. What is the tension in each strand?
250 N
if you pull horizontally on a desk with 150 N and the desk doesnt move, the friction force must be 150 N. now if you pull with 250 N so the desk slides at constant velocity, the friction force is
250 N
when a woman stands with two feet on a scale, the scale reads 280 N. When she lifts one foot, the scale reads
280 N
A 15-N force and a 45-N force act on an object in opposite directions. What is the net force on the object?
30 N
Suppose the gravitational force between two masses is 70 N. If the magnitude of one of the masses halves, what is the force between the masses?
35 N
You pull horizontally on a 50 kg crate with a force of 450 N and the friction force on the crate is 250 N. The acceleration of the crate is
4 m/s
suppose the gravitational force between two massive sphere is 200 N. If the distance between the spheres is doubled, what is the force between the masses
50 N
Suppose two people one having three times the mass of the other, pull on opposite sides of a 20 meter rope while on frictionless ice. after a brief time, they meet. The more massive person slides a distance of
5m
suppose the gravitational force between two spheres is 15 N. If the magnitude of each mass doubles, what is the force between the masses?
60 N
A sports car has a mass of 1500 kg and accelerates at 5 m/s2. What is the magnitude of the force acting on the sports car?
75000
How much force is needed to accelerate a 4 kg physics book to an acceleration of 2 m/s?
8.0
A bag of sports equipment has a mass of 10.0 kilograms and a weight of
9.8N
The acceleration produced by a net force on an object is
All of the above 1inversely proportional to the mass of the object 2 directly proportional to the magnitude of the net force 3 in the same direction as the net force.
Friction
All of the above. 1 comes from microscopic bumps that act as obstructions to the object's motion. 2 it has the name given to the force acting between surfaces sliding past one another. 3 acts in a direction that opposes the motion of an object.
A push on a 1 kilogram brick accelerates the brick. Neglecting friction, to equally accelerate a 10 kilogram brick, one would have to push
With 10 times as much force
After a cannonball is fired into frictionless space, the amount of force needed to keep it going equals
Zero since no force is necessary to keep it moving.
Suppose a particle is accelerated through space by a constant 10-N force. Suddenly the particle encounters a second force of 10-N in a direction opposite to that of the first force. The particle
continues at the speed it had when it encountered the second force
How does acceleration of an object change in relation to its mass? it is
inversely proportional
A rock is thrown vertically into the air. At the very top of its trajectory the net force on it is
its weight
By noticing that uraneous orbit is perturbed and by using the law of gravitation two astronomers independently discovered
neptune
When an object reaches terminal velocity its acceleration is
o m/s2
Friction is a force that always acts
opposite to an object's motion
Newton reasoned that the gravitational attraction between earth and the moon must be
reduced by distance
A player hits a ball with a bat. The action force is the impact of the bat against the ball, what is the reaction to this force?
the force of the ball against the bat
The reason the moon does not fall into earth is that
the moon has a sufficiently large orbital speed
An unfortunate bug splatters against the windshield of a moving car. compared to the force of the car on the bug. the force of the bug on the car is
the same
a person is attracted towards the center of earth by a gravitational force. The force with which earth is attracted toward the person is
the same
a large truck and a smal 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 tennis ball and a solid steel ball with the same diameter are dropped at the same time. which ball has the greater force acting on it
the steel ball
A tennis ball and a solid steel ball with the same diameter are dropped at the same time. In the absence of air resistance, which ball has the greater acceleration
they both have the same acceleration