A box of mass 6.30 kg is dropped from a height of 2.10 m onto a super-sized skateboard of mass 8.70 kg that rolls on a horizontal surface where no friction acts. Initially the skateboard moves at 7.00 m/s.
(a) Assume that the box stays on the skateboard. What is the final speed?
(b) The collision of the box and the skateboard lasts a time of 8.00 ms. What is the average force exerted by the skateboard on the box during the time of the collision?
J= Favg * t
The Attempt at a Solution
I already have found part a to equal 4.06 m/s. I just need help figuring out what to do with part b, which is to be reported in i-hat j-hat notation.