The ratio of useful energy output to total energy input is called energy.

the fabric of the hot air balloon can stretch, but it does not allow air to pass through it. think about the change in air density you expect as the pilot adds hear to the air in the balloon.

How are red giants different than main sequence stars?

What's the stuff called that holds a car window in place?

What is the largest component of bog soil?

Holes drilled several kilometers into Earth's crust provide direct evidence about Earth's interior in the form of a. seismic waves. b. rock samples. c. liquid iron. d. volcanic eruption.

Which of the following simple machines includes a wedge? A. axe B. file C. bolt D. ramp

What are the units of speed or velocity

List the colors of visible light in order of decreasing frequency physics

You can identify a pure substance if you know it's?

A rod of mass M and length L can rotate about a hinge at its left end and is initially at rest. A putty ball of mass m, moving with speed V, strikes the rod at angle θ from the normal and sticks to the rod after the collision.