The kinetic energy of a ball with a mass of 0.5 kg and a velocity of 10 m/s isj.

K.E. = 1/2 mv²
K.E. = 1/2 (0.5)(10)²
K.E. = 1/2 * 50
K.E. = 25 Kgm/s
This is what I know

Electoral current force mechanical advantage if the wheel and axle is 2 n and the output force is 20 n

The boat's velocity relative to the riverbank can be resolved into two components. the component going north is 2.7 m/s and the component going west is 1.2 m/s.we add these two vectors and then find the magnitude of the resultant to get the speed.the magnitude of the resultant vector from adding can be obtained by the pythagorean theorem.    to two significant figures, the boat's speed relative to the riverbank is 3.0 m/s.