Question

Choose the correct one from the following.

• A. A simple machine is a device that changes the direction or magnitude of a force.
• B. A simple machine is a device that has only one pulley.
• C. A simple machine is a device that increases human efforts.
• D. A simple machine is a device that always maintains the magnitude of a force.

Answer 1

The correct option is A

A simple machine is a device that changes the direction or magnitude of a force.

As per the definition of simple machines, it is a mechanical device that changes the direction or magnitude of an applied force which is also known as an effort. So option (d) is incorrect. Pulley is one of the simple machines which we use on regular basis.
A set of pulleys is also a simple machine. So option (b) is wrong.
A machine is designed to decrease the human efforts. So option (c) is wrong.