Question

A skydiver of mass m jumps from a hot air balloon and falls a distance d before reaching a terminal velocity of magnitude v . Assume that the magnitude of the acceleration due to gravity is g .
-What is the work (Wd) done on the skydiver, over the distance , by the drag force of the air?

-Find the power (P d) supplied by the drag force after the skydiver has reached terminal velocity v.

Answer 1

Answer:

a. Wd = ½mv²−mgd

b. Pd = -mgv

Explanation:

The skydiver losses potential energy and gains kinetic energy.

Work done by gravity

W=mg

Therefore, work done by gravity is given as

P.E= weight × height

P.E= mg × d

P.E= mgd

The work done by kinetic energy

K.E=½mv²

Then, the drag work becomes

We=K.E-P.E

We=½mv² - mgd

b. Drag power

Power is given as

Power=force × velocity

The force =weight =mg

g is negative since or is against gravity (upward motion)

Pd=F×v

Pd=-mgv