Newton's Laws
The Law of Action and Reaction
every action has an equal and opposite reaction
What is force?
the push or pull on an object
Friction
a contact force that works against the motion of objects moving past each other
John pulls a cart with a force of 150 N to the left. Julie pulls to the right on the cart with a force of 150 N.
Balanced: 0 Net Force
gravity, magnetism, and electricity
Three field forces
Law of Inertia
an object at rest stays at rest, an object in motion stays in motion unless acted upon by an outside force
The unit for force
Newton
Sliding Friction
two objects when one is sliding past the other
The car is pulling the trailer to the right with a force of 2000 N. The trailer is pulling to the left with a force of 1500 N. What is the net force?
sum of all the forces acting on an object
Net Force
Law of Acceleration
a larger force causes a larger acceleration or the acceleration of an object is directly proportional to the net force acting on it
What is field force?
a force that acts between two objects that are not touching
two objects when one is rolling relative to the other, less friction than normal
Rolling Friction
You accelerate in an track meet 12 m/s2. Your mass is 50 kg. What is the force needed to achieve this acceleration?
600 N
force that holds protons and neutrons together in the nucleus
Strong Force
What do the letters in F=ma mean?
Force equals mass x acceleration
a force that acts only when one object touches another
Contact Force
between two objects that are touching but not moving relative to each other
Static Friction
You push a boulder with a mass of 500 kg with 2500 N of force. How much acceleration is necessary?
5 m/s2
Mass
the measure of the amount of matter in an object
What is inertia?
the tendency of matter to resist a change in motion
extreme short-distance force that holds subatomic particles together inside protons and neutrons
Weak Force
This field force's strength varies in direct proportion to the masses of the objects
Gravitational Force
The gravitational pull of the earth is 9.81m/s2. If an object has a mass of 899 kg, how much would it weigh on earth?
8820 N
exists between electrically charged particles, can be an attractive or repulsive force depending on the charges of involved particles
Electromagnetic Force