Classical Mechanics Homework Set I
Pass 1 for this homework is due on Tuesday September 8, 1998.
The version to be graded is due Friday September 11, 1998.
This initial homework set is not based on any new material covered in this
course. Instead, it requires familiarity only with introductory undergraduate
mechanics. The level of difficulty and the probable length of time needed
to work out solutions are intended to be fairly typical of the subsequent
homework sets in this course.
I-A:
Work out the last assigned problem in the Classical Mechanics section of the
Kent State Physics Candidacy Exam of Tuesday September 1, 1998.
I-B:
The name Beanstalk has been applied to a
"Space Tower" scheme devised in 1960 by a Russian scientist, Yuri
Artsutanov. Follow the link to find out what is the general idea and
form of a Beanstalk.
- Find the expression for escape velocity at a distance R away
from a large body of mass M, and the radius of the circular orbit
corresponding to a period T.
- Suppose that the beanstalk counterweight has mass m, and the
whole system orbits synchronously about the large body with period T.
(T is of course one day if we consider a beanstalk on earth). Given
that we require the counterweight to move at escape velocity, find the
expression for the tension in the cable at the point of connection to the
counterweight.
- Using a qualitative or quantitative argument, explain why a tapered
cable as suggested by Jerome Pearson makes sense, and why the thickness
must be greatest at the radius of the geosynchronous orbit.
- The most likely scenario for a practical beanstalk is for transportation
to and from space colonies in independent orbit about the sun. Suppose that
the colonies are structures of radius 1 km, rotating so as to simulate
terrestrial gravity at this radius, and also suppose that launch speeds up
to 3 km/s are needed. How long should the beanstalk be?
I-C:
In 1901, Allo Diavolo introduced the circus act depicted below. Assuming
a circular loop of radius R, and taking the approximation that
Allo's pedaling just compensates for friction, (1) find the expression for the
minimum height h' needed at the top of the ramp. (2) What is Allo's
horizontal component of velocity on the ramp as a function of his horizontal
distance s from the bottom, given that the ramp height is described by
a known function h(s)? (3) Starting from this expression, find the
time taken to reach the bottom of the ramp if h(s) = a s
, where a is a constant.