Question

Two friends, Al and Jo, have a combined mass of 137 kg. At an ice skating rink they stand close together on skates, at rest and facing each other, with a compressed spring between them. The spring is kept from pushing them apart, because they are holding each other. When they release their arms, Al moves off in one direction at a speed of 1.18 m/s, while Jo moves off in the opposite direction at a speed of 1.37 m/s. Assuming that friction is negligible, find Al's mass.

Answer 1

63.4 kg

Step-by-step explanation:

This is a shock problem that must be solved with the conservation of the moment, for this we create a system formed by the two friends (Al and Jo) and the spring, so the forces that act are internal and the moment is conserved

Initial p₀ = 0

Final
`p_(f)` = m₁ v₁ + m₂ v₂

Assign Al letter 1 and Jo letter 2

p₀ =
`p_(f)`

0 = m₁ v₁ + m₂ v₂

m₁ / m₂ = - v₂ / v₁

m₁ / m₂ = - 1.37 / -1.18

m₁ / m₂ = 1,161

m₁ = 1,161 m₂

In addition, we combined mass

m₁ + m₂ = 137 Kg

(1,161 m₂) + m₂ = 137

2,161 m₂ = 137

m₂ = 63.4 kg