# Lecture30 N6

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Physics 218: Mechanics
Instructor: Dr. Tatiana Erukhimova
Lecture 30

Hw: Chapter 12 problems and exercises
Chapter 13: Prs. 1,2; Exs. 2,4
A dart, mass m, moves horizontally with a
velocity of magnitude V0. It strikes and sticks
into a wooden block, mass M. The block is hung
from a string as shown. Assume the collision of
the dart and the block takes place so quickly
that the string remains vertical during the
collision. Find H, the height at which the block
stops.
Polar coordinates
A 3000 kg spacecraft is in a circular orbit 2000
km above the surface of Mars. How much
work must the spacecraft engines perform to
move the spacecraft to a circular orbit that is
4000 km above the surface?
A ball of mass m is swung around a circle at the
end of a string of length L. The string will break
if the tension in it exceeds a critical value, Tc.
What is the largest constant angular velocity the
ball can have without breaking the string?
A ball of mass m is swung around a circle at the
end of a string of length L. What is the minimum
 the ball can have and still travel in a circle
without string becoming slack?
Have a great day!

Hw: Chapter 12 problems and
exercises; Chapter 13: Pr. 1,2; Ex. 2,4