FORCE AND ENERGY

FORCE AND ENERGY (science)

force and energy are the terms that we often use in our daily lives.

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In a volleyball game, the ball hit by the players initially goes up, but always comes down due to __________ force on our earth surface. ( please do not forget to placing a capital letter in the form of the first letter of the answer you will write or it will be showing incorrect )

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the referee on the side uses ____________ energy from his whistle to control the game. ( please do not forget to placing a capital letter in the form of the first letter of the answer you will write or it will be showing incorrect )

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Since the game is mostly played indoors, the stadium needs to be sufficiently lit. the floodlights produce a lot of ___________ (light, sound ) energy. (please do not forget to placing a capital letter in the form of the first letter of the answer you will write or it will be showing incorrect )

RECAP

we have learnt in previous lessons that push or pull are the actions tht make objects move, for example a bullock pushing a cart, man pushing a bike, a boy lifting his school bag and a girl kicking a ball. in all these cases, what makes the object move, push or pull applied on an object. let us learn about the affects that force can produce.

Affects of Force

(1) Force can make an object move.

(2) Force can stop a moving object.

(3) Force can change the direction of an object.

(4) Force can even change the shape of an object.

Force can make an object move

a force acting on a stationary object can make it move. also, a force acting on a moving object can make it move faster, if the force is applied in the same derection in which the object is moving. for example a football player kicks a ball to make it move or a boy pushing a cart to make it move forward.

Force can stop a moving object

a force acting on a moving object can slow down or stop it completely, if it is applied in the direction opposite to the direction of motion.

for example, a goalkeeper uses his hand to stop the football from rolling into the net.

Force can change the direction of a moving object

a force acting on a movng object from an angle can change th direction in which the object is moving.

for example, in cricket, a batsman hits a moving ball with such force that it changes its direction.

Force can change the shape of an object

a force acting on an object can change its shape.

have you ever kneaded dough or made chapatis ? notice how a rolling pin makes the ball of dough flat and round when you apply force.

another example is to squeeze a sponge and see how its shape changes.

Types of forces

(1) gravitational force

(2) electrostatic force

(3) magnetic force

(4) frictional force

Gravitational force

Gravitational force or gravity is the force with all objects in the universe attract each other. the gravitational force of the earth pulls an object in the air to its surface because of the earth`s gravity. gravitational force always acts in the opposite direction when a creature, an object move away from the earth`s` surface; it acts along the direction of motion of the object when it move towards the earth.

The attractive or repulsive force that acts due to the presense of ` charge' is