Acar with mass m traveling at speed v has kinetic energy k. what is the kinetic energy of a second car that has the same mass m and twice the speed of the first car? k 1.4 k 2 k 4 k

Kinetic energy, KE, is modeled by the formula , where m is the mass in kg and v is the velocity in m/s.

In this scenario, mass and one-half are constant but the velocity changes. 

You can see that by squaring twice the velocity, that is equal to four times the original KE. Therefore, the answer is 4k.

W= fd
where f is an applied force and d is the distance over which it is applied. when a parachuting skydiver is at constant velocity, he is experiencing "terminal velocity", the point at which his acceleration down is canceled out by air resistance. that means that the resisting force of the air is equal to his weight, but in the opposite direction. with this, we can solve for the work done by the force.
w = fd
w = (92.0)(9.81 m/s^2) (325)
w= 2.93 x 10^5 j
the value for work in this case is positive because it is pushing up on the skydiver, who has a downward force of gravity.
therefore the answer is 2.93 x 10^5 j