5. Answer the following.
(a) What is force? List what all force can do.
(b) What is gravity? How is it useful?
(c) Why is friction important?
(d) How can we reduce friction? Why do we need to do so?
(e) What are simple machines? Name the different types of simple machines.
Answers
Answer:
In physics, a force is any interaction that, when unopposed, will change the motion of an object. A force can cause an object with mass to change its velocity (which includes to begin moving from a state of rest ), i.e., to accelerate. Force can also be described intuitively as a push or a pull.
Answer:
a.A force can do one of four things to an object: Make it speed up - accelerate. Make it slow down - decelerate. Change its direction.
b.Gravity is very important to us. We could not live on Earth without it. The sun's gravity keeps Earth in orbit around it, keeping us at a comfortable distance to enjoy the sun's light and warmth. It holds down our atmosphere and the air we need to breathe
c.Friction always slows a moving object down. ... Friction can be a useful force because it prevents our shoes slipping on the pavement when we walk and stops car tyres skidding on the road. When you walk, friction is caused between the tread on shoes and the ground. This friction acts to grip the ground and prevent sliding.
d.Friction is a necessary evil which causes a lot of wear and tear in machine parts that move against each other. It erodes the surfaces and destroys their symmetries. Hence, in such cases it is desirable to reduce friction. Friction is reduced by lubricating surfaces to decrease the friction.
e.The simple machines are the inclined plane, lever, wedge, wheel and axle, pulley, and screw.