Question

Need and necessity of gadgets based on newton law of motion

Answer 1

The roller coasters 

are fun because of the principle of gravity. Newton's laws of motion

apply here. Gravity has a direct effect on the speed and acceleration.

The rockets take off on the basis of Newton's third law of

motion which states that for every action or force exerted there is an equal

and opposite reaction.

The Newton Gravity Sand Timer which is a standard hour glass, is

also based on Newton's laws

Some every day examples of the application of Newton's laws

are -

Seat belts become tight when a car stops quickly.

A ball rolls down a hill till another force is applied to

stop it.