Explain the differences between a physical and chemical change, and give examples of each.

Why did scientists choose carbon as a base for the atomic mass unit?

A man of mass 80 kg runs up a flight of stairs 20 m high in 10 s. (a) how much power is used to lift the man? (b) If the man's body is 25% efficient, how much power does he expend? (c) This man consumes approximately 1.

The position equation for a particle is s of t equals the square root of the quantity 2 times t plus 1 where s is measured in feet and t is measured in seconds. find the acceleration of the particle at 4 seconds.

If the boat's engine has a heat of 40,000 J, with 30,000 J exhausted into the surroundings (the heat sink), what is its efficiency? Show your work.

When a soccer ball is headed from one player #1 to player #2 across the soccer field, what is the projectile? A. player #2 B. soccer field C. player #1 D. Soccer field

Two children stretch a jump rope between them and send wave pulses back and forth on it. The rope is 4.5 m long, its mass is 0.42 kg, and the force exerted on it by the children is 71 N.

An object will only change its motion if a force is directly applied to it. is this a true statement?

Janice has just measured the density of an object. Which value is possible? (Density: D = )

Based on how the book describes a heat pump in sec 16.3 how does a heat pump prove law of conservation of energy

When a gas in a container is squeezed to half its volume, its density?