A hospital has a back-up generator to power the medical devices in case of a
power failure. Which of the following is the most likely source of mechanical
energy for the generator?
O A. Falling water
O B. Burning coal
O C. Sunlight
O
D. Gasoline or diesel fuel

Why is alternating current more effective at long–distance travel than direct current? a. the power lines are made out of conductors. b. transformers increase or decrease voltage as needed. c. the ac generator is more efficient. d. ac has lower voltage than dc.

Could someone . i have tried to solve myself but my calculation is off

Imagine that someone pushes one marble toward a motionless marble. would there still be action-reaction forces involved in the collision? how might the marbles’ motions be changed? ?