Transcript Newton`s Laws

Newton’s Laws of
Motion
Sir Isaac Newton
 Born January 4, 1643 in England
 As a young student, Newton
didn’t do well in school.
 He worked hard and continued
his education.
 Later in life, Newton contributed
ideas that became law in the
worlds of science and math.
Newton’s Law of Inertia
 “An object at rest, tends to stay at rest, and an object in
motion, tends to stay in motion with the same speed and in
the same direction, unless acted upon by an outside force.”
 Objects resist change in motion.
 The more mass an object has, the greater its inertia.
Newton’s Law of Force and Acceleration
F
=
ma
Net force on object = mass of object x acceleration
Which vehicle will accelerate more quickly? Why?
For Example…
If the force remains constant, smaller masses will have
greater acceleration compared to larger masses.
a
F=m
F=
m
a
If the force remains constant, larger masses will
have less acceleration compared to smaller masses.
For Example…
Small Mass = Greater Acceleration
Large Mass = Less Acceleration
Newton’s Law of Force and Acceleration
If the mass of an object remains constant, then
acceleration increases as the force increases.
ALWAYS identify the force, mass, and acceleration
variables to see which ones are constant.
Force
Force (N) = mass (kg) x acceleration (m/s2)
F = ma
So, what happens if you are trying to see how fast a
force can accelerate a particular mass??
Write the initial equation:
F = ma
Decide what you are solving for:
acceleration
Use math to restructure the equation:
F = ma
m m
So, what happens if you are trying to see how fast
a force can accelerate a particular mass??
The equation for acceleration is:
a=F
m
But does the equation make sense??
 What happens to the acceleration of a bicycle if the force is
increased (pedal harder)??
 What happens to the acceleration of a bicycle if the mass is
increased (having to pull friends on rollerblades)??
This can be done to find the mass of an object
being accelerated with a particular force.
Write the initial equation:
F = ma
Decide what you are solving for:
mass
Use math to restructure the equation:
F = ma
a
a
So, what happens if you are trying to see how
fast a force can accelerate a particular mass??
The equation for mass is:
m=F
a
Does it make sense?
Newton’s Law of Action-Reaction
 "For every action, there is an equal and opposite
reaction."
Reaction
Action
Newton’s Law of Action-Reaction
 All forces act in pairs.
 When one object exerts a force on a second object,
the second object exerts an equal and opposite force
on the first object.
 This is not a cause-effect relationship.
 The forces occur simultaneously.