Question

.A car of mass 1000 kg, travelling at 20m/s collides with another car B of mass 2000kg travelling at 25m/s in the same direction. After collision the velocity of car A becomes 15m/s. Calculate the velocity of car B after collision.​

Answer 1

By using the principle of conservation of momentum you will be able to get the answer.

m1u1 + m2u2 = m1v1 = m2v2

1000 × 20 + 2000 × 25 = 1000 × 15 + 2000 × y

70000 = 15000 + 2000y

y = 27.5 m/s

velocity of car B after collision = 27.5 m/s

Answer 2

Answer:

Thus, we write this as follows:

m1u1+m2u2=m1v1+m2v2……..(1)

Here, m1=1500kg is the mass of the car A.

m2=1000kg is the mass of the car B.

u1=25m/s is the initial velocity of the car A.

u2=15m/s is the intial velocity of the car B.

v1=20m/s is the final velocity of the car A.

v2=? is the final velocity of the car B.

From equation (1),

1500×25+1000×15=1500×20+1000×v2

37500+15000=30000+1000×v2

52500=30000+1000×v2

1000×v2=52500−30000

1000×v2=22500

v2=22.5m/s

Thus, the speed of the car B is 22.5 m/s.