Question

What is force ?
Define muscular, gravitational, buoyant, frictional force.
What are the advantages and disadvantages of friction :-

Answer 1

★ what is force :-

A force is a push or a pull. Force gives an object the energy to move, stop moving, or change direction. when we write with a pen we exert a force. when we peddle out bike, blow our nose, turn on a tap, chew our gum, or while swimming in a pool, we are exerting forces on other objects. we would never be able to move without exerting a force on things.

★ Muscular Force :-

Pushing and pulling objects require muscular force. it is the force applied using physical contact with an object that causes an object to bend, crack, scratch, lift etc.

★ Gravitational Force :-

Gravity is the attraction of objects towards the earth and the force with which the earth attracts the objects is called Gravitational force.

★ Buoyant Force :-

When we put a cube of ice in a glass of water, it pushes away some of the water causing the level of water to rise and the ice cube to float on water. Gravity pushes the ice cube itno the water but another force works in the opposite direction pushing the ice cube upwards. This force is called buoyant force.

★ Frictional Force :-

Friction is a force that opposes motion. Friction acts in a direction opposite to the direction of motion of the object.

Without friction, the object would continue to move at a constant speed forever.

★ Advantages of Friction :-

1) Walking :

• We are able to walk due to friction between our shoes and the ground. As we try to step forward, we push out foot backward, friction holds our shoe to the ground, allowing us to walk.
• For the same reason it's difficult to walk on slippery surfaces as the force of friction between the shoes and the surface is less.

2) Writing :

• Writing with a pencil requires friction. we couldn't hold a pencil in our hand without friction, it would slip out of our hand. The graphite pencil lead wouldn't make a mark on the paper without friction between the lead and the paper.

3) Rubbing :

• A pencil eraser uses friction to rub off mistakes written in pencil lead. Rubbing the eraser on the pencil marks wears out the eraser due to friction, whose particles gather up on the paper.

★ Disadvantages of friction :-

1) Makes movement difficult :

• Excess friction can make it difficult to slide a box across the floor, ride a bicycle or walk through deep snow.

2) Heat parts :

• The energy spent in order to overcome friction leads to liberation of a lot of heat.

3) Wears things out :

• As friction leads to production of heat, any device that has moving parts can wear out rapidly due to this heat. Lubrication is used not only to allow parts to move easily but also to prevent them from wearing out.

Answer 2

Explanation:

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