Help...please..thank you

The radius is 20cm..BTW ):

Will give brainliest! jay rides his 2.0-kg skateboard. he is moving at speed 5.8 m/s when he pushes off the board and continues to move forward in the air at 5.4 m/s. the board now goes forward at 13 m/s.a. determine jay’s mass.b. determine the change in the internal energy of the system during this process.(express your answer to two significant figures and include the appropriate units.)

Does anyone have the answers to online physics course plato course physics, semester a v3.0

During a car accident, a 125kg driver is moving at 31m/s and in 1.5s is brought to rest by an inflating air bag. what is the magnitude of the change in momentum to the driver