1. Forces and the Laws of Motion
Changes in Motion

2. Force
Force – the cause of acceleration, or the change in an object’s velocity
Causes objects to speed up, slow down, start motion, stop motion, change direction
Force is measured in Newtons (N)
1 Newton equals the amount of force necessary to accelerate a 1kg mass 1m/s2
1N=1kgm/s2
Weight is a force caused by the interaction between gravitational acceleration and an object’s mass

3. Force

4. Force Forces can act through contact or at a distance
Contact force – force that arises from the physical contact of two objects
Field force – force that can exist between objects, even in the absence of physical contact between the objects
Gravity, electromagnetic force

5. Force Diagrams
Force diagram – a diagram of the objects involved in a situation and the forces exerted on the objects
Draw arrows with the tail of the arrow on the object and the head of the arrow in the direction of the force

6. Force Diagrams

7. Force Diagrams