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Questions in physics

[Answered] A man plans to use a 2-meter crowbar to lift a rock by placing a pivot 0.8 meters from the rock. One end of the crowbar will be under the rock, and he will push down on the other end with a force of 400 N. The mass of the rock is 50 kg. 1. Will the man be able to move the rock? Show how you worked out your answer. 2. The man’s daughter says that she can move the rock although her force on the other end is only 200 N. Explain how this is possible.

[Answered] When a wave enters a new medium, it may speed up or slow down. What other properties of the wave might change when it enters a new medium?

[Answered] What two measurements are needed to determine density?

[Answered] Why does a simple oscillating pendulum not produce a vibrating sound?

[Answered] Predict what the mass would be of an object exerting a force of 45 N on a spring scale. Explain how you determined your answer.

[Answered] An astronaut lands on a new planet. The new planet’s mass is half that of the Earth and the new planet’s radius is half that of the Earth. If he weighs 500 N on Earth, what will the force of gravity be on him on the new planet?

[Answered] Earth is the third planet from the sun. Which two planets are closer to the sun than Earth is?

[Answered] Why does convection occur only in fluids?

[Answered] Apply the concept of density to explain why oil floats on water.

[Answered] Conduction is usually faster/slower in liquids and certain solids than in gases. Materials that are good conductors of thermal energy are called _______. Metals are excellent/poor thermal conductors.