1. Force equals mass times acceleration.
Newton’s Second Law
Force equals mass times acceleration.
F = ma
Acceleration: a measurement of how quickly an object is changing speed.

2. Force and Acceleration
Force is a push or a pull.
Acceleration is when the motion of an object changes.
Examples:
Speed up
Slow down
Changes direction
Mass is the amount of matter in an object.

3. Force and Acceleration
Units of Force = Newtons (N)
SI units for mass is kg
SI units for acceleration is m/s2
1 Newton (N) = 1kg * m/s2

4. 2nd Law
When mass is in kilograms and acceleration is in m/s/s, the unit of force is in Newtons (N).
One Newton is equal to the force required to accelerate one kilogram of mass at one meter/second/second.

5. What does F = ma mean?
Force is directly proportional to mass and acceleration. Imagine a ball of a certain mass moving at a certain acceleration. This ball has a certain force.
Now imagine we make the ball twice as big (double the mass) but keep the acceleration constant. F = ma says that this new ball has twice the force of the old ball.
Now imagine the original ball moving at twice the original acceleration. F = ma says that the ball will again have twice the force of the ball at the original acceleration.

6. More about F = ma
If you double the mass, you double the force. If you double the acceleration, you double the force.
What if you double the mass and the acceleration?
(2m)(2a) = 4F
Doubling the mass and the acceleration quadruples the force.
So what if you decrease the mass by half? How much force would the object have now?

7. What does F = ma say?
F = ma basically means that the force of an object comes from its mass and its acceleration.
Something very massive (high mass) that’s changing speed very slowly (low acceleration), like a glacier, can still have great force.
Something very small (low mass) that’s changing speed very quickly (high acceleration), like a bullet, can still have a great force. Something very small changing speed very slowly will have a very weak force.

8. Gravity & Weight
Gravity is the force of attraction that exists between any two objects that have mass.
The force of gravity depends on the mass of the objects and the distance between them.

9. Gravity & Weight
Weight is a force, like the push of your hand is a force, and is measured in Newtons.
The force of gravity causes all objects near Earth’s surface to fall with an acceleration of 9.8 m/s² or 10 m/s².
Your weight on Earth is the gravitational force between you and Earth.

10. Gravity and Weight How are weight and mass different?
Weight is a force, like the push of your hand is a force, and is measured in newtons.
Mass is the amount of matter in an object, and doesn’t depend on location.
Weight will vary with location, but mass will remain constant.

11. WEIGHT is a measure of the force of ________ on the mass of an object
Newton’s Second Law
WEIGHT is a measure of the force of ________ on the mass of an object
measured in __________
gravity
Newtons

12. Newton’s Second Law One rock weighs 5 Newtons.
The other rock weighs 0.5
Newtons. How much more
force will be required to
accelerate the first rock
at the same rate as the second rock?
Ten times as much

13. Newton’s 2nd Law
Newton’s Second Law states: an object acted upon by an unbalanced force will accelerate in the direction of the force.
If you kick the ball, it starts moving.
The ball accelerates only while your foot is in contact with the ball.