1. The meaning of Force
The effects of Forces
Types of Forces
Frictional Force
Elastic Spring Force
Gravitational Force

2. acting upon an object as a result of its interaction with another object

3. To apply pressure against for the purpose of moving
Pushing up
Hitting a ball
Kicking a ball
Slapping
Pushing a cart
Riding a bicycle
Punching

4. To apply force to so as to cause or tend to cause motion toward the source of the force.
Pulling grass
Pulling a dog
Fishing
Dragging
Pulling a plug
Playing Kite

11. A contact force is a force between two objects
(or an object and a surface)
that are in contact with each other.
Non Contact force is a force at a distance
It occurs between objects
not touching each other 

12. Created whenever two surfaces move or try to move across each other.

13. The surfaces of objects are never perfectly
smooth. Even a very smooth surface seen under
a microscope, is found to have hills and valleys. As they move across each other, they get snagged and it makes it harder to move.

14. Friction acts in the opposite direction to the movement

15. Friction makes it harder for things to move.

16. Friction acts to reduce the speed of a moving object.

17. Friction can also cause heat!
Rubbing sticks to make fire
Rubbing hands causes heat
Rubbing dry sticks causes forest fire
Friction can also cause heat!

18. on the texture of surfaces.
Friction is dependent
on the texture of surfaces.
Ball moves greater distance on a smooth surface than on
a rough surface because of lower friction

19. Friction is dependent on the amount of contact force
pushing the two surfaces together
Less Frictional Force
Greater Frictional Force

20. Friction between our shoes
and the floor stop us from slipping
Friction between the brakes
and wheel help bikes
and cars slow down
Friction between tires
and the road stop cars
from skidding
Lighting a match stick is possible due to the friction between the matchstick
and its cover.
We are able to write because of friction present between the paper and tip of a pen
To hold a glass of water, friction is necessary
We can not fix nail in the wood or wall
if there is no friction.
It is friction which holds the nail.
Friction is required to play the violin,
or to move a mouse on the mouse pad

21. Friction also produces heat in machines, when their parts are rubbed against
each other. This can lead to
over heating of the machine,
which may lead to
the damage of parts.
To overcome excess friction in air,
a lot of fuel is wasted in cars and airplanes
If you do not oil a bicycle the string and axes can squeak and be noisy. 
Tires wear out
Wears out the soles of shoes
Machines wear out and need
lubrication after a period of
time due to the friction
present between
the different parts of
a machine.
Produces unnecessary heat - Car engines becomes hotter because of friction.

23. Sand and gravel is strewn on slippery ground during rainy season
or snowy road
Patterns on the surface of tires
and on the soles of shoes
Putting nets
on sole shoes
to walk
on snowy or icy road
A carpet is used
to cover the tiled surface.
Road are made with rough surfaces to provide grip of vehicle tires.
Spikes are provided in the soles
of shoes used by players and athletes

24. An elastic spring force occurs when a material is stretched
or compressed.

25. Stretching and Compressing
Elastic Spring Force

26. Stretching creates a tension force which is a pulling force applied by an object when it is stretched.
Stretched Spring
Stretched Bow
Stretched Rubber Slingshot
Stretched Rubber Band

27. A compression force is a squeezing force applied to an object that can make
an object shrink.
Compressed Spring

28. Cloth Pin
Elastic Band
Stapler
Trampoline
Compressed Ball
Pins
Spring Bed

29. THE HISTORY OF GRAVITY Sir Isaac Newton wrote the Law of Gravitation
in 1687

30. Gravity or gravitational forces are forces of attraction.
Every object in the universe that has mass 
exerts a gravitational pull, or force,
on every other mass. 
Attracts each other

31. Gravity is a pulling force Gravity is measured as an acceleration
The gravity of planet Earth is measured as 9.81 m/s2

32. The weight of a body is the force of gravity acting on it
Mass is how much matter an object has
Mass is measured in grams (g)
or kilograms (kg)
Weight is measured in Newton's (N)
or kiloNewtons (kN)
Your mass stays the same if you could travel from planet to planet,
but your weight would vary depending on
how the gravity of that planet pulls on you.

33. In outer space, away from any planet or star,
an object becomes weightless