Weighty Questions
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1) If you weigh 150 lb on Earth, then your mass is about 68 kg (i.e., it
is 150 lb / 2.2 lb/kg). If you are sitting about 1 m (3.3 ft) from another
person of similar weight, then what is the gravitational force of
attraction between the two of you? At a distance of 0.1 m? 0.01 m? 0.001
m?

1.0 m = _____ N <-- equivalent to the weight of a flea!

0.1 m (1 dm) = _____ N

0.01 m (1 cm) = _____ N

0.001 m (1 mm) = _____ N


2) Calculate the gravitational force of attraction between a maximum-size 
male & female elephant (6000- & 3000kg respectively) at the following 
distances: 1.0 m; 0.1 m; 0.01 m; 0.001 m.

Elephant Facts:
http://www.nczooeletrack.org/elephants/facts.html
African elephants are the largest land animals with body growth continuing
for up to 30 years. Bulls (males) may reach a height of 9-13 feet (3-41/2
m) at the shoulder and weigh between 9,000-13,000 pounds (4,500-6,000 kg).
Cows (females) are smaller in size, averaging 7-9 feet (2.5-3 m) at the
shoulder and weighing between 4,500-7,000 pounds (2,200-3,000 kg). An
adult elephant will be almost as tall as it is long.

1.0 m = _____ N

0.1 m (1 dm) = _____ N

0.01 m (1 cm) = _____ N

0.001 m (1 mm) = _____ N


3) What is the gravitational force of attraction between the Earth ("Mass 
1") and a 150-lb person ("Mass 2") on Earth?

Earth Statistics:
Mass (kg) 5.976e+24 <-- input "Mass 1" exactly as it is shown left
Equatorial radius (km) 6,378.14, or 6,378,140 m <-- input "Distance"  
without commas, i.e., 6378140

F(G) = _____ N <-- the person's weight

a(1) = _____ m/s(2)

a(2) = _____ m/s(2) <-- gravitational acceleration (Note: The person 
accelerates toward Earth, the more massive of the two objects!)


4) The International Space Station orbits Earth at an average altitude of
~350 km. Is an astronaut really "weightless" when he or she is traveling
in a spacecraft orbiting a few hundred kilometers above the Earth's
surface? Support your answer with data & calculations (show your work).



5) If the Sun's mass is 1.9891 x10(30) kg, and the mean Earth-Sun distance 
is 1.496 x 10(6) km, then what is the gravitational force of attraction 
between the Sun and the Earth?



6) The mass of the Moon is 7.35x10(22) kg, and is 3.8x10(5) km away from
Earth. Which exerts a stronger gravitational influence on the Earth, the
Moon or the Sun? Support your answer with data & calculations (show your 
work).