Is energy absorbed or given off when an electron and a hole of a semi-conductor crystal

recombine? What are the forms of energy that can be absorbed or given off?

A skier accelerates down the hill at 3m/s2 how fast is he going in 4 seconds

A hot iron ball of mass 200 g is cooled to a temperature of 22°C. 6.9 kJ of heat is lost to the surroundings during the process. What was the initial temperature of the ball? (ciron = 0.444 J/g°C) A) 23°C B) 78°C C) 100°C D) 155°C

A model rocket is fired vertically upward from rest. its acceleration for the first three seconds is a (t) = 72t, at which time the fuel is exhausted and it becomes a freely "falling" body.

Describe how a volcano is formed at a Continental Rift. Be sure to include, in your description, what is occurring at the plate boundary.

Megan is waiting for the school bus. She sees it driving down the street straight toward her position. If the bus is moving at a constant speed, which graph shows the position of the bus relative to Megan through time?

Calculate the speed for a car that went a distance of 125 miles in 2 hours time

A small 25 kilogram canoe is floating downriver at a speed of 4 m/s. What is the canoe's kinetic energy?

A car traveling on a flat (unbanked), circular track accelerates uniformly from rest with a tangential acceleration of 1.85 m/s2. The car makes it one quarter of the way around the circle before it skids off the track.

A train travels 120 km in 2 hours and 30 minutes what is the average speed

How many constellations are there?