Studied by 4 people
Sir Isaac Newton’s (1643 - 1727) Contributions
Calculus
Light is composed of rainbow colors
Reflecting Telescope
Laws of Motion
Theory of Gravitation
Phosphorous
Kinematics
the description of how objects move without considering the reasons why they move
Dynamics
The study of the causes of motion and the reasons why a change in motion may occur
What is a force?
A pull or a push
May accelerate
May change shape
Nothing may happen
Definition of Force
A push or pull exerted on an object that can cause a change in motion
Is a vector quantity (needs a direction)
Symbol: F
Units: Newtons (N)
Defined as the amount of force required to give a 1 kg mass an acceleration of 1 m/s2
Types of Forces - General
Contact Force
a force that exists only when contact is being made
Ex: pushing a plate across a table, holding a glass
Types of Forces - General
Field Forces
a force that exists without contact being made
Ex: a book falling off a table,
Newton’s Laws of Motion
First Law
An object at rest tends to remain at rest and an object in motion tends to remain in motion (in a straight line at a constant speed - no acceleration) unless acted upon by a net force.
Often referred to as low of intertia
Inertia
The property of an object that resists changes to its motion.
When stationary, difficult to move
When moving, difficult to stop
It depends on mass.
Inertia Examples
Sudden acceleration in a car
Sudden deceleration in a car
Inertia Demonstrations
Quarter on card
Mass on string
Football
When calculating force..
remember, force has direction.
Newton’s Second Law
When a net (or unbalanced) force acts on an object, it accelerates in the direction of the net force.
The acceleration varies directly to the net force on it and inversely to its mass.
Mass and Weight
Bathroom scales measure weight - not mass
◦ Mass is the amount of matter an
object has.
◦ Weight is the force of gravity on the object.
Weight
On or near the Earth’s surface, the acceleration due to gravity, g, is constant
g = 9.8 m/s2
Force of gravity: Fg = mg
Also called an object’s weight
Always directed downward towards the center of the planet
Apparent Weight
the force an object experiences as a result of all the forces acting on it, giving it acceleration
Weightlessness
What would the scale read if the cable on the elevator broke?
Both you and the scale would be accelerating at the same rate
Newton’s Third Law
For every action force there exists a reaction force that is equal in magnitude but opposite in direction.
Recoil
Ex. Identify the action-reaction forces in the following situations
A badminton racquet hitting a birdie
A boat being rowed
A gun being fired
