Why are mercury and the earths moon so cratered?

A swimmer of mass 64.38 kg is initially standing still at one end of a log of mass 237 kg which is floating at rest in water. He runs toward the other end of the log and dives off with a horizontal speed of 3.472 m/s relative to the water.

Which of the following best describes what we mean by the universe? (A) all the galaxies in all the superclusters (B) the sum total of all matter and energy (C) a vast collection of stars that number as many as the grains of sand on all the beaches

In the rotating Earth/Moon system, centrifugal force is equal to the gravitational force, but operates in the opposite direction. True or false?

How are work, energy, and power related

How do you find input energy with only the efficiency and output energy given?

What color of light can plants "see"?

Two tiny beads are 25 cm apart with no other charges or fields present. Bead A carries 10 µC of charge and bead B carries 1 µC. Which one of the following statements is true about the magnitudes of the electric forces on these beads

A ball is thrown straight up at 20 m. What is the balls velocity as it hits the ground?

Block 1 and Block 2 have the same mass, m, and are released from the top of two inclined planes of the same height making 30 degree and 60 degree angles with the horizontal direction, respectively.

Water waves change direction when they encounter water of different depths and begin to move at different wave speeds. This is called A. reflection B. constructive interference C. the Doppler effect D. refraction