physics
posted by Raf .
A ball of 250g hits the floor at a velocity of 2,50 m/s at an angle of 70* relative to the vertical. The vertical force in function with time between the floor and the ball is:
from 0 to 50 N : from 0 to 1 sec.
from 50 N to 100 N : from 1 to 2 sec.
constant 100 N : from 2 to 3 sec.
100 to 50 N : from 3 to 4 sec.
and 50 N to 0 N : from 4 to 5 sec.
What is the velocity of the ball after the collision if the ball bounces? Give the answer in terms of unit vectors and polar notation.

I know that I have to use 1/2 mv^2 for the velocity and mgh for gravitational energy, but I'm lost from here, especially when they ask to put it in unit vectors.
Thank you