Which cannot be done by a machine a. increase force b. increase work c. change direction of force d. increase velocity

A machine cannot increase the amount of work done.

Option B

Explanation:

Machines are used to make the work easier. Generally, it is thought that machine increases the amount of work performed to complete the work soon. But it is not true as work done is a form of energy and according to conservation of energy, energy cannot be created nor be destroyed it can only be transferred.

So, as work done is a form of energy utilized to push or change the position of an object for a particular distance with the given external force, the work done cannot be changed by a machine.

But the machine makes it easier by either increasing the acting force on object or by increasing the distance at which the force is acting or by also changing the direction of acting forces on the object. Thus, machine cannot increase the amount of work done on the object for its displacement.

.) the observation by semmelweis that more mothers died of childbed fever when their doctors also worked in the morgue

current flows in a wire