Chapter 4.10, Problem 16E

The gravitational force, F, between an object and the Earth is inversely proportional to the square of the distance from the object to the center of the Earth. If an astronaut weighs 212 pounds on the surface of the Earth, what will this astronaut weigh 300 miles above the Earth? Assume that the radius of the Earth is 4000 (Round off your answer to the nearest pound.)

A skydiver weighing 120kg drops vertically from a jet flying at 4.000m. Assume the force due to air resistance to be proportional to the velocity of the skydiver, with the proportionality constant b1= 20 N⋅sec/m before the cute is opened, and b2= 100 N⋅sec/m after the chute is opened. If the skydiver opens the chute after 60 seconds of free fall, find:  a. The total amount of time elapsed between dropping out of the plane and landing.  b. The velocity of the skydiver at the instant of landing on the ground.

Hooke's Law states that the length a spring stretches is directly proportional to the weight on the spring. If a weight of 5 kg stretches a spring 12 cm, determine the weight that would stretch the spring 27 cm.