Question

Assertion:
To unscrew a rusted nut, we need a wrench with a longer arm.
Reason:
Wrench with a longer arm reduces the torque applied by the arm.
(A) Both Assertion and Reason are correct and Reason is the correct explanation for Assertion.
(B) Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion.
(C) Assertion is correct but Reason is incorrect.
(D) Assertion is incorrect but Reason is correct.

Answer 1

Hint The Moment of a force is a quantity of its disposition to let it make an entity to rotate about a particular or distinct point or axis. A moment is due to a force for not having a similar and constricting force directly through its line of action.

Complete step by step solution
Torque is the quantity of the force that can bring about an entity to rotate about the axis. Force is what makes an entity to speed up in extended kinematics. Likewise, the torque is what generates an angular acceleration. That is, torque can be explained as the rotational comparable of linear force.

The torque or moment of force is the product of force and perpendicular distance from the pivot. Therefore, longer the arm it will give more torque for small applying force and more torque will help to open screw easily. That is, the assertion is correct but the reason is incorrect.

Therefore, the assertion, that is to unscrew a rusted nut, we need a wrench with a longer arm is correct but the reason that a wrench with longer arm reduces the torque applied by the arm is incorrect.

Hence the option (C) assertion is correct but reason is incorrect is the correct answer.

Note Both the torque and the moment of force have the same unit that is , but torque is a movement of force, where in case of the moment it is a static force. Torque is used wherever there is rotation involved, where in case of moment it is used where there is no rotation.