Resolution of Forces and Friction

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Mathematical Physics  Major Grade
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REVIEW
Show your work in the space provided for partial credit.
FORMULA BANK:
For a block on an inclined plane,
d = ½at
a=
2
FX = Fwsin
For a block on an inclined plane,
v
t
FY = Fwcos
FNET = FX - Ff
FW = mg
On a horizontal surface, FW = FN
FX = Ff in a simple equilibrium
situation
Ff = FN
On an inclined plane,
FY = FN
F = ma
Over-Easy:
1. (five points) Draw and label the specified forces acting on the book in
the Figures below. Friction is present.
(a.) all the horizontal forces
I’m a
box!
(b.) all the vertical forces .
I’m a
box!
2. (three points) Draw and label the forces acting on the box on the
inclined plane in the Figure below that affect its motion along the plane.
Assume the box wants to slide down the plane. Friction is present.
3. (two points) Draw and label the forces acting on the hanging mass in
the Figure above.
MEDIUM-Rare:
4. (two points) A 2 kg box is being dragged along the floor at a constant
velocity by a force of 380 N.
(a.) Find the Normal Force
acting on the box.
(b.) Find the coefficient of
friction between the box
and the floor.
5. (one point) A bag of mass 5 kg is falling through the air with a constant
velocity of 2.5 m/s. How much air resistance is acting on the bag?
6. (one point) If the tension on the cable in the figure below is 350 N, what
is the mass of the sign?
40º
Dr. Quark
Physicist
Well-Done:
7. (two points) A 2 kg block slides down a twometer-long inclined plane in 2.5 seconds (see
figure at right). Friction is present.
(a.) How much time would it
take for the block to slide
down without friction?
28º
(b.) How much friction is
present?
OVER-Cooked:
7. Assuming that the system of
blocks wants to slide to the left
(down the 32° slope)…
B
A
32º
28º
(a.) (three points) Draw and label the forces acting on Block A that
affect its motion down the plane. Assume friction is present on
the incline Block B is on but not the one Block A is on.
(b.) (two points) Assume the conditions from Prob. A and that the
coefficient of friction between Block B and the slope is 0.6 . If
Block B has a mass of 2 kg, how much total force is trying to keep
block A from moving the system of blocks down the slope?
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