When two different observers watch a moving object,

a. they always see different motion
b. both of them always see the same motion
c. both of them see the same motion as long as both of them are moving
d. they will see the same motionvif they are in the same reference frame

Name three different units of energy used to measure heat and describe what type of situations each is usually used.

1. jay fills a wagon with sand (about 20 kg) and pulls it with a rope 30 m along the beach. he holds the rope 25° above the horizontal. the rope exerts a 20-n tension force on the wagon. how much work does the rope do on the wagon?

The electric field between square plates of a parallel-plate capacitor has magnitude e. the potential across the plates is maintained with constant voltage by a battery as they are pulled apart to twice their original separation, which is small compared to the dimensions of the plates. the magnitude of the electric field between the plates is now equal to a)e b)e/4 c)e/2 d)4e e)2e