When the atom's electrons step down to lower energy levels in a thin cloud of hot gas, what is produced?

Suppose a cyclist travels 15 kilometers during the first hour. Then the cyclist travels 33 kilometers during the next 2 hours. What is the cyclist's average speed?

You need to raise a heavy block by pulling it with a massless rope. You can either (a) pull the block straight up height h, or (b) pull it up a long, frictionless plane inclined at a 15∘ angle until its height has increased by h.

A high-speed train travels 480 km from Paris to Grenoble, France, at an average speed of 180 km/h. How long will it take to reach Grenoble? A. 0.66 h B. 3.8 h C. 0.38 h D. 2.7 h

A 100N sack of potatoes is suspended by a rope. A person pushes sideways on the sack with a force at 40N. What is the tension in the rope.

A speeding car is going 72 mi/hr. The driver hits the brakes to slow the car down to the 45 mi/hr speed limit. The car has a mass of 1.0 metric tons. What is the magnitude of the impulse on the car?

The national grid supplied a house with 18000000 J of energy in 1 hour. What was the average current supplied to the house in that hour? Write any equations that you use.

Claudia throws a baseball to her dog. Which free-body diagram shows the baseball when it's flying horizontally in midair? (Assume no air resistance.)

Which of the following substances will show the smallest change in temperature when equal amounts of energy are absorbed? water air sand concrete

The downward acceleration of a falling body on Earth is 9.81m/s2. On the moon the same quantity is 1.62m/s2. An astronaut in a space suit has a mass of 145kg.

Explain how a guitar produces sound by using the terms standing waves and resonance.