Question

A force f1 acts on a particle, so as to accelerate it from rest to a velocity v. If the force f1 is replaced by f2, which decelerates it to rest, then
a)f1 may be equal f2
b)f1 must not be equal to f2
c)f1 and f2 must be zero
d)f1 must be equal to f2

Answer 1

Heya!!

(A) is the right answer

Since, according to condition of motion under two forces, f1 and f2 must be acting in opposite directions and may be equal, not necessarily must be equal.

Hope it helps✌️✌️

Answer 2

The correct option is (A)

Explanation:

If initial speed of the particle is 0 and it accelerate from rest to a velocity v. The force acting on it is $F_1$. It is given by :

$F_1=\dfrac{mv}{t}$

If $F_1$ is replaced by $F_2$,  which decelerates it to rest, then

$F_2=-\dfrac{mv}{t}$

So, the magnitude of $F_1$ and $F_2$ may be same but their direction is opposite. Hence, the correct option is (A).

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