Question

Explain why pulling is easier than pushing with a neat sketch on a rough horizontal plane.

Answer 1

We push or pull a heavy object on a surface against the friction between object and the surface. The force of friction increases as the normal reaction of the surface on the object increases (Limiting i.e. maximum static friction, kinetic friction and rolling friction all are directly proportional to the normal reaction of the surface on the object). If surface is a level ground, this normal reaction in magnitude is equal to the weight of the object.

If a heavy object is pushed on a level road, the vertical component of the pushing force acts on the body in vertically downward direction and thus increases the effective weight of the object and therefore increases force of friction between object and the ground.

If the heavy object is pulled on a level ground, the vertical component of the pulling force acts on the object in vertically upward direction and thus reduces the effective weight of the object and therefore decreases friction between object and the ground.

We see that effective weight of the object and as a consequence friction between object and the ground in case of pulling are lower than those in case of pushing. So, it is easier to pull a heavy object than to push it on a level ground.

$F_r=frctionforce=\mu N$

In pulling normal reaction in smaller, therefore friction is smaller and it easy to pull.