1. 5.1 Forces

2. Forces Force: - a push or pull
- an action that has the ability to change motion
Forces can:
- increase or decrease the speed of a moving object
- change the direction of an object

3. How Forces Act
Direct contact
Action at a distance

4. Other Direct Contact Forces
Tension: a pulling force that acts in a rope, string, etc.
Spring Forces
Extension: a stretch, or increase in size
Compression: a squeeze, or decrease in size

5. Gravity
Gravity: the force that causes all masses to attract one another
On earth: g = 9.8 N/kg

6. Mass vs. Weight Mass Weight
Mass: a measure of the amount of matter in an object
Mass DOES NOT CHANGE
Units: grams (g) or kilograms (kg)
Weight: a measure of gravitational force
Weight CHANGES depending on location
Units: Newtons (N) or pounds (lbs)

7. A 10 kg rock has the same mass everywhere, but different weights.
Mass vs. Weight
A 10 kg rock has the same mass everywhere, but different weights.

8. Weight = mass x strength of gravity
Calculating Weight
Weight = mass x strength of gravity
W = m x g
On Earth:
g = 9.8 N/kg
What is g on the moon?

9. Force Vectors Arrow points in the direction of the force.
Length shows the strength of the force.
INCLUDE A SCALE.