1. 2 FORCE
2.10 INTRODUCTION TO FORCE
2.11 EFFECTS OF FORCE
2.12 TYPES OF FORCE
2.13 REPRESENTATION OF FORCE
2.14 BALANCED FORCES
2.15 UNBALANCED FORCES
2.16 RESULTANT FORCE
2.17 FINDING RESULTANT FORCES
2. 2.10 INTRODUCTION TO FORCE
Force is what is applied to a body to change its state of rest,
movement or direction.
Force is expressed in Newtons (N) and is measured using a Newton
meter.
Analogue newton meter Digital newton meter
3. 2.11 EFFECTS OF FORCE
Force can change
(1)shape of an object
(2) size of an object
(3)speed of an object
(4) direction of movement of an object
Note : Force cannot change mass of an object since mass is
the amount of matter in an object and it will remain
unchanged.
4. 2.12 TYPES OF FORCES
Type Description
Weight
Gravitational force (applied by the Earth)
Friction Due to two surfaces in contact which acts in the opposite
direction of movement of an object, it opposes the movement
Tension Due to an elastic material
Drag Opposing force due to the medium which slows down the object (air resistance, water
resistance)
Thrust Force applied by the engine
Upthrust Upward force applied by the medium in which the object is (air, water) due to difference
in pressure
Reaction force Force applied by a rigid surface at the point of contact
5. 2.12 TYPES OF FORCES(CONT’D)
Frictional force acts opposite to the direction of movement of the
object. It can be reduced by making the surfaces smooth, lubricating
(applying oil) and also streamlining the object.
Drag increases with increase in the speed of the object.
Task 1: Compare the two types of trains below:
6. 2.13 REPRESENTATION OF FORCE
Force is represented by a line and an arrow, length of the line
representing the magnitude of the force (how much the force is) and
arrow showing direction.
Length can be measured accurately following a suitable/given scale.
Example: A force of 20 N acting towards east using a scale 1 cm = 5N
7. 2.14 BALANCED FORCES
Two or more forces are said to be balanced if total of the forces acting
in one direction is the same as the total of the forces acting in opposite
direction.
8. 2.15 UNBALANCED FORCE
Two or more forces are said to be unbalanced if total of the forces
acting in one direction is different from the total of the forces acting in
opposite direction.
9. 2.16 RESULTANT FORCE
It is a single force that has the same effect on an object to which more
than one force is applied.
10. 2.17 FINDING RESULTANT FORCE
A Forces acting along the same line and same
direction:
Add the forces to get the magnitude
Direction of the resultant is direction of any of
the forces
B Forces acting along the same line and in
opposite directions:
Subtract smaller from larger forces to obtain
magnitude.
The direction of resultant force will be the
direction of the bigger force.
