A ball is moving at 4m/s and has a momentum of 40 kg m/s. What is the balls mass

The charge on a charged sphere is: a)concentrated at its centerb)distributed uniformly throughout its volumec)clustered on its centerd)distributed uniformly over its surface

What sort of waves exhibit the doppler effect?

If a car has a speed of 20 m/s, how long will it take to go 155 m? a. 3100 s b. 135 s c. 2.1 s d. 7.8 s