Question

Help Meeeeee

Two kids are roller skating. Amy, with a mass of 55 kg, is traveling forward at 3 m/s. Jenny, who has a mass of 40 kg, is traveling in the opposite direction at 5 m/s. They crash into each other and hold onto each other so that they move as one mass. How fast are they traveling?

Answer 1

0.4 m/s

Step-by-step explanation:

From the law of conservation of momentum, the sum of initial momentum equals the sum of final momentum

Momentum, p=mv where m is the mass and v is the velocity

`m_1v_1+m_2v_2=(m_1+m_2)v_c` where
`v_c` is the common velocity,
`v_1` and
`v_2` are velocities of Amy and Jenny respectively,
`m_1` and
`m_2` are masses of Amy and Jenny respectively.

Taking forward direction as positive, opposite direction is negative hence
`v_1` is 3 m/s while
`v_2=-5 m/s`

`55 kg* 3 m/s +(40 kg* -5 m/s)=(55 kg+40 kg)v_c`

`95 kg v_c=-35 kg.m/s`

`v_c=\frac {-35}{95}=-0.368421053  m/s\approx -0.4 m/s`

Therefore, they travel at 0.4 m/s in the direction of Jenny's movement