91Ó°ÊÓ

Problem 37

Margie, who weighs \(543 \mathrm{N},\) is standing on a bathroom scale that weighs \(45 \mathrm{N}\). (a) With what force does the scale push up on Margie? (b) What is the interaction partner of that force? (c) With what force does the Earth push up on the scale? (d) Identify the interaction partner of that force.

Problem 38

Refer to Problem \(36 .\) Consider the skydiver and parachute to be a single system. What are the external forces acting on this system?

Problem 40

A young South African girl has a mass of \(40.0 \mathrm{kg}.\) (a) What is her weight in newtons? (b) If she came to the United States, what would her weight be in pounds as measured on an American scale? Assume \(g=9.80 \mathrm{N} / \mathrm{kg}\) in both locations.

Problem 41

A man weighs \(0.80 \mathrm{kN}\) on Earth. What is his mass in kilograms?

Problem 42

An astronaut stands at a position on the Moon such that Earth is directly over head and releases a Moon rock that was in her hand. (a) Which way will it fall? (b) What is the gravitational force exerted by the Moon on a 1.0 -kg rock resting on the Moon's surface? (c) What is the gravitational force exerted by the Earth on the same 1.0 -kg rock resting on the surface of the Moon? (d) What is the net gravitational force on the rock?

Problem 45

How far above the surface of the Earth does an object have to be in order for it to have the same weight as it would have on the surface of the Moon? (Ignore any effects from the Earth's gravity for the object on the Moon's surface or from the Moon's gravity for the object above the Earth.)

Problem 46

Find and compare the weight of a \(65-\mathrm{kg}\) man on Earth with the weight of the same man on (a) Mars, where \(g=3.7 \mathrm{N} / \mathrm{kg}.\) (b) Venus, where \(g=8.9 \mathrm{N} / \mathrm{kg} ;\) and (c) Earth's Moon, where \(g=1.6 \mathrm{N} / \mathrm{kg}.\)

Problem 47

Find the altitudes above the Earth's surface where Earth's gravitational field strength would be (a) two thirds and (b) one third of its value at the surface. [Hint: First find the radius for each situation; then recall that the altitude is the distance from the surface to a point above the surface. Use proportional reasoning.]

Problem 48

During a balloon ascension, wearing an oxygen mask, you measure the weight of a calibrated \(5.00-\mathrm{kg}\) mass and find that the value of the gravitational field strength at your location is 9.792 N/kg. How high above sea level, where the gravitational field strength was measured to be $9.803 \mathrm{N} / \mathrm{kg},$ are you located?

Problem 49

At what altitude above the Earth's surface would your weight be half of what it is at the Earth's surface?