During convection of air currents,

a. all air rises.

b. cool air sinks.

c. warm air sinks.

d. air is cooled by a heat source.

A 25.0 kg block is initially at rest on a horizontal surface. A horizontal force of 75.0 N is required to set the block in motion, after which a horizontal force of 60.0 N is required to keep the block moving with constant speed.

If you put a pencil in a cup of water, it looks as if it is bent and larger in the water. This is because waves A) can reflect off the surface. B) are absorbed instead of reflected. C) bend around a barrier, like light does.

Two boys are standing on the two sides of a stationary boat. One has a mass of 70 kg and the other has 50 kg. If they jump at 4ms-1 at a time, the boat will go in either direction.

a stone is tied to a string and whirled around in a circle at a constant speed. is the string more likely to break when the circle is horizontal or when it is vertical?

Which technology is intended to work at a distance of about 5 to 10 centimeters with transmission speeds of 250 Kbps?

Forgetting takes place only in short-term memory.

What is the simplest relationship between the angular wavenumber k and just one of the other kinematic variables? Express your answer using only one of the other kinematic variables plus constants like π.

The pilot of an airplane notes that the compass indicates heading west. The airplane's speed relative to the air is 100 km/h. The air is moving in a wind at 25.0 km/h toward the north.

How do you get a resultant factor? A. Add two or more vectors B. Add two scalars C. Multiply two scalars D. Multiply two vectors

A panpipe is made of five pipes. The longest pipe is 25 centimeters long and the shortest is 5 centimeters long. Which of these pipe produces the highest-frequency sound and why?