Question

Boat A and Boat B have the same mass. Boat A’s velocity is three times greater than that of Boat B. Compared to the kinetic energy of Boat B, the kinetic energy of Boat A is

Answer 1

The kinetic energy of an object is half its mass times velocity squared. Thus, if the boats have the same mass, but boat A has three times the velocity, boat A has 9 times the kinetic energy.

Answer 2

Explanation:

Let m is the mass of both boats A and B. It is given that, Boat A’s velocity is three times greater than that of Boat B.

Let the velocity of boat B is x. So, the velocity of Boat A is 3 x. Kinetic energy of Boat A is:

$K_A=\dfrac{1}{2}mv_A^2=\dfrac{1}{2}m(3x)^2=9(\dfrac{1}{2}mx^2)$

Kinetic energy of boat B is :

$K_B=\dfrac{1}{2}mv_B^2=\dfrac{1}{2}m(x)^2$

$K_B=(\dfrac{1}{2}mx^2)$

$K_A=9\times K_B$

So, the kinetic energy of boat A is 9 times the kinetic energy of boat B. Hence, this is the required solution.