Answer:
Step-by-step explanation:
Givens
Mass: 1450 kg
vi = 0
a = 5 m/s^2
vf=?
Formula
KE = 1/2 m v^2
d = vi * t + 1/2 a t^2
a = (vf - vi)/t
Solution
The final KE = 0 because the final velocity = 0 (The concrete wall saw to that).
Second formula
d = vi*t + 1/2 a t^2
20 = 0 + 1/2 * 5 * t^2
40 = 5*t^2 Divide by 5
40/5 = t^2
8 = t^2
2√2 = t
Third formula
5 = (vf - 0)/2√2 Multiply by 2√2
5* 2√2 = vf
10√2= vf
First formula
KE = 1/2 m * (10√2)^2
KE = 1/2 1450 * 100*2
KE = 1450 * 100 2 and 1/2 cancel out.
KE = 145000
This means that the change in KE is 145000 Joules or 145 kJ