Question

how much work is required to make a 1400 kg car increase its speed from 10 m/s to 20 m/s?
what average force is required if the car travels 15 m during this speed change?​

Answer 1

work = change in KE (1/2 mv^2)

10+at = 20
10t + 1/2 at^2 = 15

Answer 2

So would the first one be
Ke= 1/2mv2^2-1/2mv1^2
Ke= 1/2m(v2-v1)^2
Ke= 1/2(1400)(20-10)^2
Ke= 70000 J