What does critical mass depend on

A heat pump absorbs heat from the cold outdoors at 3°c and supplies heat to a house at 20°c at a rate of 30,000 kj/h. if the power consumed by the heat pump is 3 kw, the coefficient of performance of the heat pump is

The amount of energy a person uses at rest is known as the

One of the primary components of fertilizer is___ which can be harmful if it gets in drinking water.

A thin lens is made from a material with refractive index of 1.20. This lens may be used in either air (n = 1.00) or water (n = 1.33). Which of the following is true? A.

The runner had an initial vertical velocity of - 0.7 m/s and an initial horizontal velocity of 3.6 m/s. If the forces were applied over a period of 0.2 seconds, what are the runner's final vertical and horizontal velocities?

A wave with a frequency of 30 Hz has a wavelength of 40.5 m. How fast is the wave traveling?

A soccer ball is sitting in the middle of a soccer field during a game. When the referee blows his whistle, one of the players runs toward the ball and kicks it as hard as he can.

A body with v=20m/s changes its speed to 28m/s in 2sec. its acceleration will be

Charge: A piece of plastic has a net charge of + 2.00 μC. How many more protons than electrons does this piece of plastic have? (e = 1.60 * 10-19 C)

How much heat is needed to raise the temperature of 6g of water by 18oC?