P112 Spring 2008
Homework #11
Reading: 11.111.3, 10.410.7
Not all concepts will be covered in class – you are responsible
for all material in the reading and in the homework problems.
Problems:
1.
A ladder 5.0 m long rests against a frictionless
vertical wall with its lower end 3.0 m from the wall.
The ladder weighs 160 N. The coefficient of static
friction between the foot of the ladder and the ground
is 0.40. A man weighing 740 N climbs slowly up the
ladder.
a) What is the maximum frictional force that the
ground can exert on the ladder at its lower end?
b) What is the actual frictional force when the man
has climbed 1.0 m along the ladder?
c) how far along the ladder can the man climb before
it starts to slip?
2
. Show that the total energy of a satellite in circular
orbit is half its potential energy.
3.
A projectile is fired straight up from the surface of
the earth with an initial speed v=8km/s. Find the
maximum height it reaches, neglecting air resistance.
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 Fall '07
 LECLAIR,A
 Force, Mass, Potential Energy, Work, B B B B C C C C C P P P P

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