Question

Dan is gliding on his skateboard at 2.00 m/s . He suddenly jumps backward off the skateboard, kicking the skateboard forward at 7.00 m/s (as measured by an observer on the ground). Dan's mass is 40.0 kg and the skateboard's mass is 7.00 kg .

Answer 1

The velocity of Dan is 1.13 m/s.

Step-by-step explanation:

Given that,

Initial velocity of skateboard and Dan = 2.00 m/s

Velocity of skateboard = 7.00 m/s

Mass of Dan m= 40.0 kg

Mass of skateboard M= 7.00 Kg

Suppose How fast is Dan going as his feet hit the ground?

We need to calculate the initial velocity of Dan

Using conservation of momentum

`(m+M)v_(i)=mv_(f)+Mv_(f)`

Put the value into the formula

`(40.0+7.00)*2.00=40.0* v_(i)+7.00*7.00`

`v_(i)=((40.0+7.00)*2.00-7.00*7.00)/(40.0)`

`v_(i)=1.13\ m/s`

Hence, The velocity of Dan is 1.13 m/s.