Give reasons why :
(a) Travelling bags have wheels.
(b) Iron pipes are fitted on an inclined plane for pushing up heavy loads.
(c) We should take care of machines.
(d) We should use a pulley to draw water from a well.
(a) Travelling bags have wheels because the wheel is a simple machine which reduces our effort, so that we can easily pull the travelling bag from one place to other.
(b) Iron pipes are fitted on an inclined plane for pushing up heavy loads because iron pipes have a cylindrical shape which is similar to a wheel. A wheel is a simple machine that reduces our effort, so it is easy to push up heavy loads.
(c) We must take care of machines to minimize their wear and tear.
(d) A pulley is used to reduce our effort by changing the direction of the force acting on the water bucket. Therefore, we should use a pulley to draw water from a well.