A weight lifter holds 900 N (about 200 lb) over his head. Is he doing work on the weights? Did he do any work on the weights? Discuss.

How much work is required to laft a 6.D-log hachpack. $1.9 \mathrm{~m}$ to put it on?

Which of the following objects has the greatest kinetic energy? (4.2)

(a) an object with a mass of $4 \mathrm{~m}$ and a velocity of $v$ (b) an object with a mass of $3 \mathrm{~m}$ and a velocity of $2 v$ (c) an object with a mass of $2 \mathrm{~m}$ and a velocity of $3 \mathrm{v}$ (d) an object with a mass of $m$ and a velocity of $4 v$