Convection currents form when warm air rises and cold air sinks. What causes the warm air to rise and the cold air to sink? A. a difference in climate B. a difference in density C. a difference in weather D. a difference in substance

An astronaut drops a feather from 1.2m above the surface of the moon. If the acceleration of gravity on the moon is 1.6 m/s, how long does it take the feather to hit the moon's surface

Which two statements explain how water weathers and erodes rock? A. Water gathers in oceans. B. Water seeps into the soil. Water evaporates in the Sun. D Water freezes in cracks in rocks E Water carries matter downstream.

Which concept are described in the theory proposed by Hess

True or false? a physical change is a change of matter from one form to another without a change in chemical properties

How is thermal energy transferred during conduction? Check all that apply. Thermal energy is transferred between particles that are not touching each other. Thermal energy is transferred between particles that are in direct contact with each other.

Which of the following best characterizes the free energy change ΔG for an endothermic reaction under physiological conditions? A. The sign of ΔG is positive B. The sign of ΔG is zero C. The sign of ΔG is negative D.

In a recent hockey game, one player (m=100kg) was moving at a velocity of 8 m/s when he ran into another player (m=300kg) who was at rest (v=0m/s). After the collision, the two players were stuck together (moving with the same velocity).

In a laser, electrical energy is changed to light energy, and a small amount of the energy is wasted as heat. Describe the total amount of the heat in the system (using the conservation of energy).

What is the name for a star and planets held together by gravity? A. solar system B. galaxy C. black hole D. supernova

When a car turns a corner on a level road, which force provides the necessary centripetal acceleration? 1) gravity 2) normal force 3) air resistance 4) tension 5) friction