4. Normal human body temperature is 310 K. (a) What is the peak wavelength emitted by a person with this temperature?
(b) What part of the spectrum does that wavelength lie in?
(c) If the surface area of a person is about 1.5 m2, what is their luminosity?
(d) How does that luminosity compare to a 100W(109erg s−1) light bulb?

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

When seismic waves hit a fault, the waves are reflected off the fault. seismograph can detect these reflected seismic waves. geologists then use these data to map the fault's length and depth