math
posted by Vinitha on .
The kinectic energy E, of a toy car is directly proportional to the square of its velocity v. The difference in the kinectic energy of the toy car when it is travelling at 15cm/s and 20cm/s in 10 J. Find the kinectic energy of the toy car when it is travelling at 12cm/s thanks :)

Kinetic energy at velocity v
Ek(v)=Kv²
Since
Ek(20)Ek(15)=10 j = K(20²15²)=175K
we solve for K to get
K=10/175
Ek(12)=(10/175)*12² j
=8.2 j.