A 50kg bicyclist on a 10kg bicycle speeds up from 5.0m/s to 10m/s. What was the total kinetic energy after accelerating?​

It is really hard for me right know

Abatter hits a 0.140-kg baseball that was approaching him at 30 m/s and, as a result, the ball leaves the bat at 40 m/s in the reverse of its original direction. the ball remains in contact with the bat for 2.0 ms. what is the magnitude of the average force exerted by the bat on the ball?

Ascientist wants to test ways to reduce pollution in lake . what is the bestway of doing this