Answer:
Total momentum before collision
P1 =.4 * 3.5 = 1.4 ignoring units here
Total momentum after collision
P2 = .6 * V - .4 * .7 = .6 V - .28
.6 V = 1.4 + .28 momentum before = momentum after
V = 2.8 cm/sec
In 5 sec V moves 2.8 cm/sec * 5 sec = 14 cm
Force = mass times acceleration
F = 21000 x 36.9 = 774900
Therefore, 774900N force is required.
Force = (mass) x (acceleration)
= (0.025 kg) x (5 m/s²)
= 0.125 Newton
