Name: ______________________

Quiz 4

02/22/2005

Ch. 4-5

1)
A
man pulls a box with a massless rope at an angle of 30 degrees to the
ground. The box has a mass of 100kg
and the static coefficient of friction μ_{s}=0.6
and a kinetic coefficient of friction μ_{k}=0.3. (note: Weight
and tension are forces and forces are vectors.)

a)
Draw
two free body diagrams one for the box and one for the rope.

b)
What
is the weight of the box?

c)
What
is the normal force on the box?

d)
What
is the maximum friction force on the stationary box?

e)
What
is the minimum pulling force needed to move the box?

f)
What
is the pulling force required to keep the box moving at constant speed?

g)
What
is the tension on the rope when the box is moving at a constant speed?

2)
A
300kg sled is on a 30-degree hill. The
kinetic coefficient of friction μ_{k} between the sled and snow is
0.1.

a)
What
is the net force on the sled?

b)
If
the sled is started moving with a velocity of 1m/s, will it continue to move?

c)
What
is its speed after 10s?