LAWS
The Law of Inertia
Objects at rest remain at rest and objects in motion continue in a straight line at a constant velocity unless acted on by an outside force.
what is a Force
a push or a pull
what is the gravitational acceleration constant for g at the surface of the earth?
9.81m/s2
what do the arrows on a free body diagram represent
The magnitude of the forces acting on the object
what is a contact force
Act only when one object touches another object
How did Newton first discover gravity?
He watched an apple fall from a tree / hit him on the head
Formula for Newton's 2nd Law of motion?
F=MA
what is Fg in the weight formula?
Weight (the force of gravity acting on an objects mass)
If a bag of coffee has a mass of 2kg on earth, what is its weight?
Fg=mg
Fg= (2) (9.81) = 20 N
How is the object depicted in a free body diagram
box circle or dot
What is the ”field” in a field force?
area around an object in which other things may feel a force exerted by the object
What are the action-reaction pairs on a boat propeller churning through the water?
propeller pushing on the water (action) and water equally and oppositely pushing on propeller (reaction)
What is Newton's 3rd Law of Motion
For every action force there is an equal and opposite reaction force
what is centripetal force?
A force that accelerates an object toward the center of circular motion
What is the net force of an car with a mass of 1255kg that is accelerating 5.2m/s2 to the right?
F=ma
F=(1255kg)(5.2) = 6,526 N
Draw a free body diagram of a guy in a parachute accelerating down toward the ground. What forces are involved?
Drag (air-resistance/friction)
Gravity pushing down
Normal force
what is the weakest of the friction forces? why?
Rolling friction; it greatly reduces the friction between the surface and the object in contact
what is sliding friction?
The frictional force that exists between two objects in motion relative to each other
name for Newton's second law of motion?
law of acceleration
what is normal force?
An upward force acting in a direction perpendicular to the surface where two objects make contact
If the car’s engine supplies a force of 6526 N to the right, what is the acceleration of the car with a mass of 1255kg?
F=ma
A=f/m
A= 6526N/1255kg
A= 5.2m/s2
What type of forces affect a helicopter hovering over the landing pad?
Normal force
Gravity
(balanced force)
What is a fundamental force?
The forces that appear to underlie all known forces in nature
what is an example of centripetal force?
gravity holding the planets in orbit around the sun
what does Newton's law of gravity explain
Gravity is a field force acting between two objects
what is a Field force? list all types we talked about
gravity, magnetism, electricity
two students push a 30kg box. one pushed right with 80N while the other pushes left with 30N. What is the net force?
80N-30N = 50N
What is the difference in a balanced force and an unbalanced force on a free body diagram
Balanced force has equal arrow lengths unbalanced has different lengths showing the acceleration
What is the force that acts between the masses of any two objects?
Gravity
What kind of force must a change in motion be initiated by?
Unbalanced force