Question

A 0.350-kg ice puck, moving east with a speed of 5.16 m/s , has a head-on collision with a 0.950-kg puck initially at rest. Assume that the collision is perfectly elastic.

A) What is the speed of the 0.350-kg puck after the collision?

Express your answer to three significant figures and include the appropriate units.

B) What is the speed of the 0.950-kg puck after the collision?

Express your answer to three significant figures and include the appropriate units.

Answer 1

Let m₁ be the mass of moving ice puck and its initial speed be v₁ .

If this moving puck of mass m₁ collides with another ice puck of mass m₂ which is at rest and the collision is elastic,

then we have by conservation of momentum,

m₁ u₁ = m₁ v₁ + m₂ v₂   .................................(1)

where v₁ and v₂ are speeds after collision of mass m₁ and m₂ respectively

if collision is elastic, energy is conserved. Hence by conservation of energy we have

............................(2)

By solving eqn.(1) and eqn.(2) for unknowns v₁ and v₂ , we get

........................................(3)

...................................(4)

By substituting respective masses and initial speed of 0.35 kg ice puck in equations (3) and (4),

we get speeds of ice pucks after collision as given below

Speed of 0.35 kg ice puck after collision is :-

Speed of 0.95 kg ice puck after collision is :-