Question

The variable force exerted by the spring is given as, F = k.x (where ‘k’ is a positive constant and ‘x’ is the change in length). A box under the influence of 50 N net force is moving towards the spring.

Assertion (A): The value of ‘x’ when the forces acting on the block are balanced will be 50/k.

Reason(R): A body will remain in a state of rest or in uniform motion, until and unless it is acted upon by a unbalanced external force.

• A. Both (A) and (R) are true and (R) is not correct explanation of (A).
• B. (A) Is false but (R) is true. ​
• C. (A) Is true but (R) is false.
• D. Both (A) and (R) are true and (R) is correct explanation of (A).​

Answer 1

The correct option is A

Both (A) and (R) are true and (R) is not correct explanation of (A).

• Force produced by the spring when compressed, F = k x (towards right)
• Force acting on the box (towards left) = 50 N
• For balancing,

F = k x = 50

x = 50/k

• The change in the length of spring will be equal to 50/k. Therefore, the assertion is true.
• The reason is also true but, however, it is not the correct explanation of assertion.