Why do scientists believe that dark matter exists even though it cannot be seen?

True or False: If the Stirling engine increases the entropy of the universe when the cycle is run clockwise, it will decrease the entropy of the universe when it is run counterclockwise as a heat pump.

Land masses that move on Earth are called: a. Continents b. Tectonic continents c. Tectonic plates d. Rock Masses

A wave transfers energy from the source of the energy

A force F = 94.9 N acts at an angle α = 35◦ with respect to the horizontal on a block of mass m = 29.3 kg, which is at rest on a horizontal plane. The acceleration of gravity is 9.81 m/s 2. If the static frictional coefficient is µs = 0.

5. The moon's gravity is one-sixth that of the earth. What is the period of a 0.50 m long pendulum on the moon?

8. A force of 80 pounds on a rope is used to pull a box up a ramp inclined at 100 from the horizontal. The rope forms an angle of 330 with the horizontal. How much work is done pulling the box 25 feet along the ramp?

A raindrop has a mass of 5.4 * 10-7 kg and is falling near the surface of the earth. Calculate the magnitude of the gravitational force exerted (a) on the raindrop by the earth and (b) on the earth by the raindrop.

As an astronaut travels towards Earth, her weight A. decreases because gravity decreases. B. decreases because her mass decreases. C. increases because gravity increases. D. remains the same because her mass remains the same.

Lightning often strikes water. a. True b. False

How much work must be done on a 10 kg snowboard to increase its speed from 4 m/s to 6 m/s?