I know what dark matter is, but what exactly is dark energy and what does it do?

A 40 N crate rests on a rough horizontal floor. A 12 N horizontal force is then applied to it. If the coecients of friction are μs=0.5 and μk=0.4, the magnitude of the frictional force on the crate is:

Which of these activities performed by a chemist is primarily based on an understanding of physics? using an indicator to determine if a solution is an acid, base, or neutral testing the molar concentration of a solution checking whether a given

A batter swings at a baseball. The action force is the bat hitting the ball with a force of 5N. What is the reaction force?

Nuclear power is the only energy source which gives off radiation. a. True b. False

The term used to describe how light is reflected from a mineral's surface is a. fluorescence. b. streak. c. density. d. luster.

A receiver is in a jet flying alongside another jet that is emitting 2.0 x 106 Hz radio waves. If the jets fly at 268 m/s, what is the change in frequency detected at the receiver?

Dark matter has been detected by its

The catcher catches a. 5 kg baseball traveling at 40 m/s and the glove is pushed back 10 cm. What average force did the catcher put on the ball?

Describe the climate and name the climate zone at alaska; portland, oregon; and key west, florida.

If a river is 20 feet wide in nature and needs to be scaled to one-tenth its real size, how wide should it be in a model?