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

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

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

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

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 

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

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.

Friction acts in the opposite direction to the movement

Friction makes it harder for things to move.

Friction acts to reduce the speed of a moving object.

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!

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

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

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

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.

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

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

Stretching and Compressing Elastic Spring Force

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

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

Cloth Pin Elastic Band Stapler Trampoline Compressed Ball Pins Spring Bed

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

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

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

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.

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