Question

Assertion :A horse has to pull a cart harder during the first few steps of his motion. Reason: The first few steps are always difficult.

• 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. Both Assertion and Reason are incorrect

Answer 1

Answer: (C)

The limiting value of static friction is slightly more than the kinetic friction. Thus more force is required to overcome the static friction than to overcome kinetic friction. Once the object starts to slide, then the surface applies only kinetic friction on the block which makes the motion a little easier.

In the horse-cart case, the ground applies the static friction on the cart at rest. So, the horse has to apply more force to start the motion and after the motion starts, then less force is applied on the cart.

If however, the surface is smooth, friction in negligible and the first few steps also practically require the same effort as when in motion.

Hence, the assertion is correct but the reason is incorrect.