Exam 3 Flashcards
Newton’s First Law
A body will remain at rest or continue to move with a constant speed in a straight line unless acted upon by an outside force.
Outside forces
Any forces that are external and will change the momentum of a system.
A push or pull by one body on another
Force
Newton’s Second Law
Acceleration is caused by a net force and is proportional to the magnitude of the force, and in the direction of the force.
A force that is causing a body to speed up
Propulsive force
This force is positive in the positive direction and negative in the negative direction.
Propulsive force
A force that is causing a body to slow down.
Braking force
This force is negative in the positive direction and positive in the negative direction.
Braking force
The force on a body due to gravity
Weight
Formula for weight
Weight = (mass)(acceleration of gravity)
Acceleration of gravity
-9.81 m/s^2
How many newtons in a pound?
1 lb. = 4.45 N
How many newtons in a kilogram-meter/second^2
1 N = 1 kgm/s^2
The cause of acceleration
A net (effective) force
Newton’s Third Law
For every force, there is an equal and opposite reaction force.
The force created when two bodies are touching each other.
Contact force
A force of equal in magnitude and opposite in direction of the initial force.
Reaction force
The equal and opposite force that the ground applies back on a person.
Ground reaction force
This opposes motion between two objects in contact.
Friction
Will always be parallel to the contact area.
Friction
Caused by irregularities in the surfaces between two objects.
Friction
Are always acting in different bodies.
The force and reaction forces.
Formula for Newton’s Second Law
Force = (mass)(acceleration)
The product of average force and the time that the force is applied.
Impulse