Forces

Forces

Secondary 3

​Learning objectives

​1.Identify how forces affect motion

2.Identify how the resultant force changes the motion of an object

3.Differentiate between mass and weight

4.Define the relationship between force, mass and acceleration

5.Define motion in circular path

6.Identify the effect of air resistance to the motion of free falling object

7.Express the momentum and impulse of the force

8.Calculate the resultant force

​Forces and motion

​Whenever we push or pull an object a force acts upon them and makes them move from one place to another.

​Hence, force can –

1. initiate motion in a motionless object

2. change (increase or decrease) the velocity of the moving object

3. alter the direction of a moving object

4 change the shape and size of an object

​Force Quantities

​1. Forces are vector quantities because they have both size and direction.

​2. Forces are measured in newtons (N)

​3. Small forces can be measured using a spring balance (or newton meter)

​Newton as a founder of Law of motion

​FORCE, MASS AND ACCELERATION

​3rd Law of Motion

​Balanced and unbalanced force

​Balanced forces:

If the forces acting on an object are balanced then the object will either remain stationary or continue to move with a constant speed

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​Unbalanced forces:

If the forces acting on an object are unbalanced then the object will change its speed.  It will begin to move, speed up, slow down or stop.