Science, Force and Motion
What is the acceleration if a 3 kilogram rock was thrown with 90 Newtons?
30 m/s2. You divide the mass by the force thrown.
If a person is pushing a cart with 300 Newtons and the cart accelerates at 0.5 m/s2, what is the mass?
600 Newtons. You divide the acceleration by force.
A 30 kilogram bike accelerates at 3 m/s2. With what force was the person pedaling?
90 Newtons. You multiply the mass (30 kilograms) by the acceleration ( 3 m/s2).
What has more inertia, a light feather or a heavy truck?
A heavy truck, because since a truck has more mass and weight, it will take more energy to change it's direction and speed, while if you have ever seen a feather, it changes speed and direction almost instantaneously.
What is equilibrium?
A state of physical balance.
Momentum is the product of A. Mass and Velocity B. Acceleration and Velocity C. Mass and Acceleration D. Mass
A. Mass and Velocity
If two objects of different mass have the same non zero momentum, A. The one with less mass will have the greater kinetic energy B. The one with more mass will have the greater kinetic energy C. They will have the same kinetic energy D. The one with the higher speed will have greater mass E. The one with the lower speed will have the greater kinetic energy
A. The one with less mass will have the greater kinetic energy
Potential energy is the energy possessed by an object due to A. Its momentum B. Its position C. Its velocity D. Its acceleration E. Its shape
B. Its position
If an object cuts its speed in half, how much momentum will it have? A. the same amount as before B. twice as much as before' C. one half as much as before D. four times as much as before E. one fourth as much as before
C. One half as much as before
To find the (blank) of an object, you have to specify both its speed and direction. A. Acceleration B. Mass C. Velocity D. Length E. Position
C. Velocity
A car at initially at rest accelerates in a straight line at 3 m/s2. What is the speed after 2 seconds? A. 0 m/s B. 5 m/s C. 3 m/s D. 6 m/s E. 2 m/s
D. 6 m/s
If an object is moving, then the magnitude of its (blank) can not be 0. A. Speed B. Velocity C. Acceleration D. A and B E. A, B, and C
D. A and B
The property of a moving object to continue moving is what Galileo called: A. Velocity B. Speed C. Acceleration D. Inertia E. Direction
D. Inertia
A book is at rest on top of a table. Which of the following is correct? A. There is no force acting on the book. B. The book has no inertia. C. There is no force acting on the table. D. The book is in equilibrium E. The inertia of the book is equal to the inertia of the table.
D. The book is in equilibrium
According to Newton's First Law of Motion: A. an object in motion eventually comes to a halt B. an object at rest eventually begins to move C. an object in motion moves in a parabolic trajectory unless acted on by a net force D. an object at rest always remains at rest E. an object at rest remains at rest unless acted on by a net force
E. An object at rest remains at rest unless acted on by a net force
What does Newton's Third Law describe?
For every action, there is an equal and opposite reaction.
What is friction?
Friction is a force that exists at the boundary between any two pieces of matter that are in contact with each other.
What is The Law of Inertia?
It is given that name because inertia is the tendency of an object to resist any change in motion until an unbalanced force acts on it.
What is the unit of measurement for momentum?
Kilogram meters per second (kg m/s). The equation for momentum is p = mv
What is the unit of measurement for mass?
Kilograms, or grams. The equation for mass is m f/a
What is the unit of measurement for velocity?
Meters per second (m/s). The equation for velocity is v = d/t (d = distance and t = time)
What is the unit of measurement for acceleration?
Meters per second squared (m/s2). The equation for acceleration is a = f/m
What does Newton's First Law describe? Tell in words
Newton's First Law describes inertia, which is an object's resistance to change it's motion or direction. An object's motion can not change unless a greater force acts on the object.
Describe what happens if you are riding a skateboard and you hit a curb.
Newton's First Law of Motion states that you will fly off your skateboard because your body's inertia wants you to still keep moving in the same direction and speed.
Describe what happens when you try and push a heavyweight boxer and when he pushes you.
Newton's Second Law of Motion describes that if you put force on a bigger force, force will be put back on you. Since the heavyweight boxer has more mass, you might not have enough force to make him accelerate. But if the heavyweight boxer pushes you, since the bigger force is pushing you, then you will accelerate in the direction that the bigger force pushed you in.
Using one of Newton's Laws, explain why heavier objects require more force than lighter objects to move or accelerate them?
Newton's Second Law of Motion describes that something with more mass moving at the same speed as an object with lighter mass will require more force to change it's speed or direction.
What does Newton's Second Law describe?
Newton's Second Law of Motion describes the change in motion is a result of an unbalanced force. If the net force of an object is unbalanced (not 0) then the object will accelerate.
Why do Newton's Second and Third Law contradict?
Newton's Second Law talks about how there is a net force acting on a single object. In Newton's Third Law, there are always two forces acting on a pair of different objects.
Describe what happens when you shoot a gun.
Newton's Third law of Motion describes that when you shoot a gun, the action of the bullet firing out of the gun in one direction forces the gun back in the opposite direction because of the power of the bullet.
What is the unit of measurement for force?
Newtons. The equations for force is F = ma
What would happen if you throw a baseball into outer space?
Since there is no air or friction into outer space, then the inertia of the baseball would keep it moving at the same speed and direction forever into outer space.
What happens when a bat hits the baseball?
The baseball pushes the bat back. This is Newton's Third Law of Motion.
What is the result of an applied bigger force?
The bigger the force that is applied to an object, the greater the resulting acceleration.
What would happen if there was no friction between any two objects?
The inertia of the moving object would keep it moving the same way and speed and direction forever until a bigger force stops it or changes it's direction.
What is the momentum if a rock at a velocity of 10 m/s was thrown with a mass of 10 kilograms?
The momentum is 100 kg m/s
A force of 6N from the right is pushing an object. A force of 15N is pushing the object from the left. What is the net force?
The net force is 9 Newtons.
What happens if you push on an object?
The object will push or pull back in the opposite direction, but with the same amount of force.
What is net force?
The overall force acting on an object.
What happens when an object applies force on a second object?
The second object applies the equal force in the opposite direction.
What is the velocity if a car with momentum of 10000 kg m/s and a mass of 1000 kilograms?
The velocity is 10 m/s
What happens when an applied force is equal is size to, but in the opposite direction of the frictional force?
There is a balanced force, so the object will keep moving at a constant speed. The combined net force will be 0, because the same amount of force are on both sides, but in the opposite direction of.
What did Isaac Newton first discover?
There is no single force.
A circus clown throws a pie at 0.5 m/s. The other clown throws a pie at 1 m/s. The first pie has a mass of 2 kgs, and the other pie has a mass of 1 kgs. Which has greater momentum?
They have an equal amount of momentum, because you have to multiply the velocity by the mass. If you do this, you will find that both pies have the same momentum.
What do you need to do to equally change the motion of two objects of different mass?
To change the motion of two objects of different mass, more force must be applied to the more massive object. If weight is applied to the wagon, you have to push harder to speed it up because now it has more inertia.
What do you need to do to keep an object moving at a constant speed in the presence of a frictional force?
To keep an object moving at a constant speed in the presence of a frictional force, a force needs to be applied that is equal in size to, but in the opposite direction.
Using one of Newton's Laws of Motion, why should we wear seatbelts?
We should wear seatbelts because if you do not wear a seatbelt in a car accident, then your body will continue moving at the same speed and direction until you eventually fly out the window. This is Newton's First Law of Motion.
If you hold a backpack in your hand, the force of gravity pulls it down. What force keeps it from falling to the ground?
Your hand is keeping the backpack from falling to the ground, because while the backpack is pulling down, your hand is pushing the backpack up to prevent it from falling. This is Newton's Third Law of Motion.