When we push or pull the lawn mower with force F at angle θ with horizontal, the force of push or pull can be resolved into two rectangular components:
(i) F cosθ, the horizontal component which helps it to move in forward direction.
(ii) F sinθ, the vertical component of force.
In case of pull, F sinθ acts in vertically upward direction which decreases the normal reaction and hence force of friction decreases.
Since in case of pull, force of friction is less than that in the case of push, hence it is easy to pull than to push.
Mass of each ball, m = 0.05 kg
Initial velocity of the ball = 6 m/s
Magnitude of the initial momentum of the ball, p1 = 0.05 x 6
= 0.3 kg m/s
After collision, the balls change their directions of motion without changing the magnitudes of their velocity.
Final momentum of each ball, pf = - 0.3 kg m/s
Impulse imparted to each ball = pf - pi = -0.3 -0.3 = -0.6 kg m/s
The negative sign indicates that the impulses imparted to the balls are opposite in direction.