The document discusses Newton's Second Law of Motion, which states that the acceleration of an object depends on the net force acting on it and its mass. It can be expressed by the equation Force = mass x acceleration (F=ma). The document provides examples of using the equation to calculate force, mass, or acceleration when two of the three values are known.

1. FORCE To cause an object to change velocity (ie to accelerate) we need to apply a force. Small force = small acceleration Double the force = double the acceleration Force Acceleration Force Acceleration

2. Small force = small acceleration Same force, half the weight = double the acceleration Force Acceleration Same force, double the weight = half the acceleration Force Acceleration Acceleration Force

3. Newton’s Second Law The idea that acceleration depends upon how big the force is, and how heavy the object, is called Newtons Second Law of Motion It can be stated in the equation: Force = mass x acceleration F = ma Force is measured in newtons (N) Mass is measured in kilograms (kg) Acceleration is measured in m/s 2

4. Newton’s Second Law F = ma can be rearranged: a = F m = F m a

5. What force is required to accelerate a 1500 kg car at 3 m/s 2 ? m = 1500 kg a = 3 m/s 2 F = ma = 1500 x 3 = 4500 N What force is applied to a 300 g cricket ball that accelerates at 20 m/s 2 ? m = 0.3 kg a = 20 m/s 2 F = ma = 0.3 x 20 = 6 N FORCE: EXAMPLES (1)

6. A force of 8 N is applied to a mass of 2 kg. What is the acceleration? F = 8N m = 2 kg a = F m = 8 2 = 4 m/s 2 A force of 200 N causes an object to accelerate at 5 m/s 2 . What is its mass? F = 200 N a = 5 m/s 2 m = F a = 200 5 = 40 kg FORCE: EXAMPLES (2)