Question

How does the proper inflation of tyre save fuel?
A. Normal reaction decreases.
B. Normal reaction decreases.
C. Sliding contact with the road decreases.
D. Sliding contact with the road increases.

Answer 1

Hint: There are two main types of frictional force: sliding friction and rolling friction. Only rolling friction works on a properly inflated tyre but on an improperly inflated tyre both sliding friction and rolling friction works, this leads to the consumption of more fuel.

Complete answer:
The force of friction can be seen all around us, this is the force that gives us the ability to walk, to hold things, etc. Friction force opposes the motion
There are many types of friction forces that exist in nature: sliding friction and rolling friction.

Sliding friction – When two objects are in contact with each other and one of the objects starts to slide over the other, then a force of friction comes into play, this force of friction is called sliding friction.

Rolling friction – Now consider two objects that are in contact with each, let one be spherical and one be flat, now if the object rolls and moves over the surface of the flat object a force of friction will generate, but this time the friction will be rolling friction.

Suppose if the spherical object did not rotate and moved over the flat object by sliding, then the frictional force would be sliding friction.

Now we know that rolling friction for a body is always less than sliding friction. For example, rolling a gas cylinder (rolling friction) is much easier than dragging it (sliding friction).
When the tyre is properly inflated the tyre is more circular so only rolling friction comes into play. When the tyre is not properly inflated the tyre is not circular therefore both sliding friction and rolling friction comes into play. So, the motion of the object consumes less fuel when the tyre is inflated and this saves more fuel.

So an inflated tyre saves more fuel because the sliding friction decreases.

So, the correct answer is “Option C”.

Note:
The motion of objects is much smoother as the objects roll over the surface it is in contact. You may have seen ball bearings (small round balls) made of either plastic or iron embedded in the joints of machines, the ball-bearing is spherical and hence reduces the sliding friction in the joints of the machine.