201
Problem 8.
Earth's orbit
Mars' orbit
your orbit
Homework Problems
1 . Roy has a mass of 60 kg. Laurie has a mass of 65 kg. They are 1.5 m
apart.
(a) What is the magnitude of the gravitational force of the earth on Roy.
(b) What is the magnitude of Roy’s gravitational force on the earth.
(c) What is the magnitude of the gravitational force between Roy and
Laurie.
(d) What is the magnitude of the gravitational force between Laurie and
the sun.
2. During a solar eclipse, the moon, earth and sun all lie on the same
line, with the moon between the earth and sun. Define your coordinates
so that the earth and moon lie at greater x values than the sun. For each
force, give the correct sign as well as the magnitude. (a) What force is
exerted on the moon by the sun. (b) On the moon by the earth. (c) On
the earth by the sun. (d) What total force is exerted on the sun. (e) On the
moon. (f) On the earth.
3. Suppose that on a certain day there is a crescent moon, and you can
tell by the shape of the crescent that the earth, sun and moon form a
triangle with a 135
°
interior angle at the moon’s corner. What is the
magnitude of the total gravitational force of the earth and the sun on the
moon.
moon
earth
sun
4. How high above the Earth’s surface must a rocket be in order to have
1/100 the weight it would have at the surface. Express your answer in
units of the radius of the Earth.
5. The star Lalande 21185 was found in 1996 to have two planets in
roughly circular orbits, with periods of 6 and 30 years. What is the ratio of
the two planets’ orbital radii.
6. In a Star Trek episode, the Enterprise is in a circular orbit around a
planet when something happens to the engines. Spock then tells Kirk that
the ship will spiral into the planet’s surface unless they can fix the engines.
Is this scientifically correct. Why.
SA solution is given in the back of the book.A difficult problem.
A computerized answer check is available.
.
A problem that requires calculus.
Homework Problems