(II) A meteorite has a speed of $90.0\ \text{m/s}$ when $750\ \text{km}$ above the Earth. It is falling vertically (ignore air resistance) and strikes a bed of sand in which it is brought to rest in $3.25\ \text{m}$. (d) How much thermal energy is produced?

"A ball is thrown straight up. Neglecting air resistance, which statement is not true regarding the energy of the ball? (a) The potential energy decreases while the ball is going up. (b) The kinetic energy decreases while the ball is going up. (c ) The sum of the kinetic energy and potential energy is constant. (d) The potential energy decreases when the ball is coming down. (e) The kinetic energy increases when the ball is coming down."

A coil spring of mass m rests upright on a table. If you compress the spring by pressing down with your hand and then release it, can the spring leave the table? Explain using the law of conservation of energy.

(II) If it requires $7.5\ \text{J}$ of work to stretch a particular spring by $2.0\ \text{cm}$ from its equilibrium length how much more work will be required to stretch it an additional $4.0\ \text{cm}$?

(II) A $66.5\text{-kg}$ hiker starts at an elevation of $1150\ \text{m}$ and climbs to the top of a peak $2660\ \text{m}$ high. (c ) Can the actual work done be greater than this? Explain.

(II) A $66.5\text{-kg}$ hiker starts at an elevation of $1150\ \text{m}$ and climbs to the top of a peak $2660\ \text{m}$ high. (b) What is the minimum work the hiker must do?