My midterm is tomorrow and I have a couple questions that I need to study. Ive tried and tried and cannot figure these out.

1) A ball is dropped from a roof and takes 3.0s to reach the ground. Calculate the elevation of the roof above the ground in meters. (neglect air resistance)

2) A car with a mass of 1500-kg changes its speed from 10.0 m/s to 30.0 m/s during a 10.0s- interval. Calculate the net average force acting on the car during the 10.0s-interval.

1 answer

1) d= 1/2 a t^2 solve for t.

2) a= deltaV/time

but force= m*a = m * above.