The acceleration of gravity on Earth is approximately 10 m/s 2 (more precisely, 9.8 m/s 2). If you drop a rock from a tall building, about how fast will it be falling after 3 seconds?

The total number of stars in the observable universe is about

What is the difference between energy and power?

The greater the wavelength of light, the greater its energy.

If you are driving at 30 miles per hour and increase your speed to 60 miles per hour, you quadruple your kinetic energy.

All galaxies beyond those local to the Milky Way appear to be receding from us.

Modern telescopes are capable of seeing bright galaxies up to about

Grass appears green because

If we observe one edge of a star to be redshifted and the opposite edge to be blueshifted, what can we conclude about the star?

Momentum is defined as