Question

A 48.5 kg student runs down the sidewalk and jumps with a horizontal speed of 4.25 m/s onto a stationary skateboard. The student and skateboard move down the sidewalk with a speed of 4.05 m/s. a) Find the mass of the skateboard. Answer in units of kg.

Answer 1

2.39 kg

Step-by-step explanation:

There is conservation of momentum here in this problem so we will use the following problem:

`m_1u_1+m_2u_2=(m_1+m_2)v`

where the mass of the student
`m_1` is 48.5 kg,

the mass of the skateboard
`m_2` is
`m_2` kg,

the initial speed of the student
`u_1` is 4.25 m/s; and

the speed of the student and skateboard
`v` is 4.05 m/s.

So substituting the given values in the above formula to get:

`(48.5*4.25) + (m_2 * 0) = (48.5 + m_2 ) * 4.05`

`206.125=196.425+4.05m_2`

`206.125 - 196.425 = 4.05m_2`

`m_2=(9.7)/(4.05)`

`m_2=2.39`

Therefore, the mass of the skateboard is 2.39 kg.