Given :
A 1200 kg car initially traveling at 20 m/s increases its speed to 28m/s.
To Find :
How much work did the cars engine have to do to cause this change.
Solution :
We know, work done is given by :
Work Done = Final Kinetic Energy - Initial Kinetic Energy
[tex]Work \ Done = \dfrac{mv_f^2}{2} - \dfrac{mv_i^2}{2}\\\\Work \ Done = \dfrac{1200 \times 28^2}{2} - \dfrac{1200\times 20^2}{2}\\\\Work \ Done = 230400\ J\\\\Work \ Done = 230.4 \ kJ[/tex]
Therefore, work done by car engine is 230.4 kJ.
