A $95$ kg quarterback accelerates a $0\mathrm{.}42$ kg ball from rest to

$24$ m$/$s in $0\mathrm{.}083$ s$.$ What is the specific power for this toss?

$69.|||$ An elevator weighing $2500$ N ascends at a constant speed of $8\mathrm{.}0$ m$/$s$.$ How much power must the motor supply to do this?

$70.||$ Humans can produce an out$-$ put power as great as $20$ W$/$kg during extreme exercise. Sloths are not so energetic. At its maxi$-$ mum speed, a $4\mathrm{.}0$ kg sloth can climb a height of $6\mathrm{.}0$ m in $2\mathrm{.}0$ min. What$$s the specific power for this climb?

General Problems

$71.||$ A $550$ kg elevator accelerates upward at $1\mathrm{.}2$ m$/$s$2$ for the first $15$ m of its motion. How much work is done during this part of its motion by the cable that lifts the elevator?

$72.||$ The energy yield of a nuclear weapon is often defined in terms of the equivalent mass of a conventional explosive. $1$ ton of a conventional explosive releases $4\mathrm{.}2$ GJ$.$ A typical nuclear warhead releases $250,000$ times more, so the yield is expressed as $250$ kilotons. That is a staggering explosion, but the asteroid impact that wiped out the dinosaurs was significantly greater. Assume that the asteroid was a sphere $10$ km in diameter, with a density of $2500$ kg$/$m$3$ and moving at $30$ km$/$s$.$ What energy was released at impact, in joules and in kilotons?

$73.||$ A $2\mathrm{.}3$ kg box, starting from rest, is pushed up a ramp by a $10$ N force parallel to the ramp. The ramp is $2\mathrm{.}0$ m long and tilted at $17.$ The speed of the box at the top of the ramp is $0\mathrm{.}80$ m$/$s$.$ Consider the system to be the box $+$ ramp $+$ earth.

How much work W does the force do on the system?

What is the change $$K in the kinetic energy of the system?

What is the change $$Ug in the gravitational potential energy

of the system?

What is the change $$Eth in the thermal energy of the system?