Question

A block slides on a table pulled by a string attached to a hanging weight. In case 1 the block slides without friction and in case 2 there is kinetic friction between the sliding block and the table. In which case is the tension in the string the biggest? Please explain.

Answer 1

The tension in the string with friction would be the biggest because of the involvement of the force of gravity. This would result in that the friction force that is acting on the system. There is no friction in the frictionless system, and only the force of gravity is relevant.

Answer 2

Answer:

In case 2

Explanation:

Thinking process:

The friction is a force that tends to oppose motion.

In case 1, the block slides without friction. This means that the surface is a smooth surface. Thus, the net force needed to pull the string is minimal.

In case 2, there is kinetic friction between the sliding block and the table. Now, the kinetic friction is given by the formula:

$F = \muN$$\mu N$

where, $\mu$ = coefficient of friction and N = normal force.

Thus, the net force needed:

$F_{net} = F_{pull} - \mu N$

Thus, the force is larger in case 2.

Therefore, the tension is larger in case 2.