Question

Q.3B)Give reasons (any 3)
a)Travllers bags have wheels.
b)Machines have to be maintained
c)Why we see any object?
d)Why should we save energy?​

Answer 1

Answer:

1. Traveller's bag has wheels so that it can be dragged easily because of reduced friction between the ground and the wheel. Thus, the wheel, a simple machine, helps to decrease the effort to be applied on the load which is a bag here.

2. A machine is composed of many parts. These parts rub against one another when in use. Due to this, these parts wear out with time. ... Thus, machines should be sent for maintenance check at fixed interval of time to ensure their proper working.

3 .We see any object because of reflection of light. When light, strikes a body, get reflected and received by human eye, the image formed in retina is what brain process and tells you that there is an object there.