Question

Is it ever possible that after an elastic collision (where a moving mass (1) strikes a stationary mass (2)) that the two objects will have exactly the same final speeds? If so, how must the two masses compare? (Hints, 1st : there are two possibilities as to how the speeds could be equal, 2nd : equations below should be helpful).V1f=V1o (m1-m2/m1+m2) V2f=V1o (2m1/m1+m2)

Answer 1

Answer:

Step-by-step explanation:

It is possible that after an elastic collision a moving mass (1) strikes a stationary mass (2) and the two objects will have exactly the same final speed.

During an elastic collision, the momentum and kinetic energy are both conserved. Since one of the object is a stationary object, its velocity will be zero hence the other moving object will collide with the stationary object and cause both of them to move with a common velocity. The expression for their common velocity can be derived using the law of conservation of energy.

Law of conservation of energy states that the sum of momentum of bodies before collision is equal to the sum of momentum of the bodies after  collision.

Since momentum = mass*velocity

Before collision

Momentum of body of mass m1 and velocity u1  = m1u1

Momentum of body of mass m2 and velocity u2  = m2u2

Since the second body is stationary, u2 = 0m/s

Momentum of body of mass m2 and velocity u2  = m1(0) = 0kgm/s

Sum of their momentum before collision = m1u1+0 = m1u1 ... 1

After collision

Momentum of body of mass m1 and velocity vf  = m1vf

Momentum of body of mass m2 and velocity vf  = m2vf

vf is their common velocity.

Sum of their momentum before collision = m1vf+m2vf ... 2

Equating 1 and 2 according to the law;

m1u1 = m1vf+m2vf

m1u1 = (m1+m2)vf

vf = m1u1/m1+m2

vf s their common velocity after collision. This shows that there is possibility that they have the same velocity after collision.