Kinetic energy is proportional to the square of the speed which means if you double the speed it gets 4 times larger and if you triple the speed it gets 9 times larger and so on. Therefore, in this case the new kinetic energy is
K = 9 * 1715.7 = 15441.3
You can also show this analytically as follows:
K = (1/2)* m * V^2
for the initial case we have
K_1 = 1715.7 = (1/2)* m * V_1^2
and for the second case
K_2 = (1/2)* m * V_2^2 = = (1/2)* m * (3* V_1) ^2
Dividing the two yields:
K_2 / K_1= (V_2/V_1)^2 = 3^2 = 9
Therefore,
K_2 = K_1 * 9
