Q3)
Force can change the state of motion of objects. Give an example for only
three of the following changes in the states of motion of objects.
i
)
ii)
iii)
iv)
From rest to motion
From motion to rest
Change in direction
Change in speed
3 Marl
Answers
Answer :-
A ball cannot move on its own, neither can a chair or a table. All non-living objects are stationary unless a force is acting on them. You need to have an engine to generate force in order to make it move, you need to kick the ball which is a form of applied force in order for the ball to fly into the goal. The chair will not move unless you move it. All these are examples of how force plays a huge role in our daily life.
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Explanation:
According to law of inertia or Newton's first law of motion, a body in state of rest or of uniform motion remains in state of rest or of uniform motion unless it is acted upon by an external force. Hence a body in uniform motion required no force to keep them in uniform motion.
Given that force = mass x acceleration
Constant speed means there is no acceleration, therefore if acceleration = 0 force is also 0.
So a force is not necessary to maintain constant speed, assuming no friction.
In deep space, for example, objects will zoom along at a constant speed with no force on them whatsoever. That results from Newton's First law of motion, which states a body in motion tends to stay in motion unless acted on by a net force.
But in most cases, when v = constant and it requires a force F to maintain that constant speed, it's because there is a braking force of friction or air drag trying to stop the body from moving. And that's why a push or pull is necessary to maintain a constant speed, to offset those braking forces.