The presentation is meant for middle school science students. It is appropriate for class 7 and 8 students

1. PHYSICS: GRADE 8
LEARNING EPISODE-2
~LALIT KISHORE, PLENUM
SCHOOL, HP
Effects of force

2. Force vs visible effects
 A force is felt/experienced by its 2 main effects. It
causes ...
 Change in the state of motion and
 Change in shape or size
 In the case of a number of forces acting on an
object,...
 Effects are produced by the net force
 Net force is also called the ‘resultant force’

3. Invisible effects of force
 At times, effects of force are not visible
outwardly on the object, but are felt by
the applier of the force
 In that situation,... the phrase ‘tends to
change’ is used with the two effects
 Exactly, the force is defined as...The vector
physical quantity that produces or
tends to produce the change in the
state of motion or shape is called force

4. Examples of the ‘force that tends to change’
 A person pushing the wall: Wall
does not move but applied force
is felt by the muscles of the
person
 A car stuck in mud
 A heavy barrier not moved by a
vehicle
 A person trying to stop a moving
railway engine

5. Experiment of spring balance
 Students are
demonstrated the working
of spring balance for
visible change of length /
extension by applying load
/ weight as force
 Extension is directly
proportional to force
enables force to be
measured or quantified

6. Examples of changes from rest to motion
 A car starts after its engine is switched on
 A ball is thrown by a player
 A ball kicked from the centre of the field
 A rocket is fired from a launching pad
 An arrow is shot from a bow
 A bullet is fired from the gum

7. Examples of changes from motion to rest
 Brakes are applied to a car
 A ball is caught by a player
 An electric fan is switched off
 A bullet hits the sand bag
 A iron ball dropped in jar filled with
water

8. Vocabulary for puzzles: Make a word-search
puzzle
 Experience
 Tend
 Cause
 State
 Speed
 Striking
 Net
 Resultant
 Bouncing