What does the term heat death refer to?
a. a danger of increasing entropy
b. the hot and fiery end to the universe
c. the unavailability of energy to do work
d. a theoretical violation of the second law of thermodynamics

When you drop a pebble from height a it reaches the ground with speed v if there is no air resistance. from what height should you drop it so it will reach the ground with three times the speed? (a) 9m (b) 3m (c) 6m (d) 18m

Sawyer is studying diffraction. he draws a diagram of a plane wave to show how light waves travel. which best describes sawyer’s error? the wave fronts should be perpendicular to the direction in which the waves move. the arrow showing the direction of movement of the waves should be pointing to the left. the arrow showing the direction of movement of the waves should be pointing downward. the wave fronts should be both parallel and perpendicular to the direction in which the waves move.

What is the name of the perceived change in a sound wave’s frequency due to motion between the observer and the sound source?