NCERT 5th Class (CBSE) Science: Force and Energy – Simple Machine

Question: What is a wheel and axle? Give examples.

Answer: A wheel and axle consists of a wheel rigidly attached to a rod (called axle). When one rotates the wheel, the axle also rotates.

Eg. – The crank used to raise a bucket of water from a well, a screw driver, a door knob and the steering whole of are.

Question: What is a pulley? What are its different types? Give examples

Answer: A pulley consists of a whee with a grooved rim, with a rope, chain or belt running round it. The wheel rotates around a stationary axle. A pulley can be of two types fixed and movable.

Fixed pulley:

The axle is fixed to some kind of support like a hook or a well. This pulley changed the direction of the force and makes the work easier.

Eg.- to lift a bucket of water from a well, to raise a flag to the top of a flaghole.

Movable pulley:

The axle is not fixed to any kind of support. It is free and movable. It is free and movable. This pulley helps to lift heavy loads with less efforts. It is usually used in combination with a fixed pulley.

Eg. – Machine like a crane uses both fixed and movable pulleys to lift heavy loads.