If you lift a 80 N book 50 cm off the floor, how much work did you do? 1. 0

2. 4000 J

3. 40 J

4. 1.6 J

A man pushes a couch a distance of 0.75 m. If 450 J of work is done, what is the magnitude of the force applied?

1. 16.9 J

2. 45

3. 1350 J

4. 2700 J

Phase changes are chemical changes. true or false

Amoving electron has kinetic energy k1. after a net amount of work w has been done on it, the electron is moving one-quarter as fast in the opposite direction. (a) find w in terms of k1. (b) does your answer depend on the final direction of the electron's motion?

Why is rain likely when warm, moisture-laden air meets cold air? a) the lighter warm air will rise and cool down, causing condensation and rain. b) the cold air moves faster and pushes the warm air away, causing condensation and rain. c) the moisture in the warm air condenses on contact with the cold air, causing rain to fall. d) the cold air mixes with the warm air, reducing its temperature causing moisture to condense.