1. Newton’s First Law of Motion
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 unbalanced force.
This tendency to resist changes in their state of motion is described as INERTIA

2. Newton’s 2nd Law F = mass x acceleration F = m a
The acceleration of an object is directly proportional to the net force acting on the object and is inversely proportional to the mass of the object. In other words:
F = mass x acceleration
F = m a

3. F m a Newton’s 2nd Law Units
Measurement Unit Force N Mass kg Acceleration m/s2

4. Newton’s 3rd Law of Motion
Whenever one object exerts a force on a second object,
the second object exerts an
equal and opposite force
on the first.
Action-reaction
Force Pairs
For every action there is an equal and opposite reaction

5. Action-Reaction Forces come in pairs
If you push on a box, the box pushes back on you
In the opposite direction

6. Example #1 A baseball pushes a glove to the left
What is the reaction force?

7. Example: Newton’s 3rd Law
Ex: Bird uses its wings to fly. Action: Wings push air downwards Reaction: Air pushes the bird upwards Equal Force in opposite directions

8. Example: Newton’s 3rd Law
Ex: Interaction between a baseball and bat Action: Baseball forces the bat to the left Reaction: The bat forces the ball to the right
Action-reaction
Force Pairs

9. Example: Newton’s 3rd Law
Ex: Interaction between tires on car and road Equal Force in opposite directions
Action-reaction
Force Pairs
For every action there is:
an equal (in size) & opposite (in direction) reaction

10. Mass vs. Weight MASS is a measure of the amount of matter in an object
Mass will not change as you move from place to place
WEIGHT is a measure of the gravitational force exerted on an object
(the force with which Earth’s gravity pulls on a quantity of matter)
The force varies from place to place
Ex: Weight of an object will be different on Earth than on the moon

11. Fg vs. Mass Lab
Purpose: To graphically and mathematically determine the relationship between Fg and mass of an object.
What will be our independent variable?
What will be our dependent variable?
How will we measure force?
How will we measure mass?

12. Post-Lab Results
Mass (kg)
Force of Gravity (N)
Calculated Slope