Answer the following question in brief.
Why do the load carrying heavy vehicles have large number of wheels?
We know, `"Pressure" = "Force"/"Area"`
So, greater the area of contact between two surfaces, lesser will be the pressure. So, the load carrying heavy vehicles have large number of wheels so that the pressure on the road is reduced due to larger contact area. Also, using large number of wheels ensures that the force due to the load is shared among the tyres and no single tyre is under stress.