Statics Test Review Answers
Example Problems (these aren’t question straight off the test!!! I’m not that
nice!!)
1. Is it easier to push or pull the box?
T=10N
30 (
FA=10 N
30 (
5 kg
5 kg
FF= FN
Force Diagram:
Ty
FN
Tx
Force Diagram:
FN
FF
FF
Fg
FN=Fg – Ty
Normal force is decreased, therefore
friction is decreased which makes objects
easier to pull than to push.
FAx
Fg
FAy
FN = Fg + FAy
Normal force is increased, therefore
friction is increased which makes
objects harder to push than to pull.
2. Which provides less “strain” or force on the ropes? Put them in order of least force to
most force.
A, B, C
A.
C.
B.

10 kg
10 kg
10 kg
=30
=60
Fg = 98N for all boxes.
FORCE DIAGRAMS:
A.
T1=49N
Fg=98N
T2=49N

T1 + T2 = Fg & T1 = T2
B.
T1y=49N
T1x
T2y=49N
T1x
T2x
cos  = T1y
T
Rearranged  T = 49N = 56.6N
T1y=49N
cos 30
T

T1 & T2 = 56.6 (larger than A)
=30
Fg
C.
T1x
T1y=49N
cos  = T1y
T
Rearranged  T = 49N = 98N
T1y=49N
cos 60
T2y=49N
T1x
T2x
T

=60
Fg
T1 & T2 = 98N (larger than A & B)
3. Draw force diagrams for min and max for the following situations:
A.
B.
T
Tmax:
Mmax:
TMIN:
MMIN:
M
A. Tmax:
Tmin:
FN
T
FN
FF
T
FF
Fgy
1kg
Fgx
Friction working against T
Fgx
Fgy
Friction working with T
B. Mmax:
M
1kg
FN
T
T
FN
FF
Fgx
Fgy
FF
Fgx
Fgy
If M has the maximum amount of mass that it possibly can, then if you were to just barely
increase it, it would slide down the incline. Friction is working against the M being able to
pull the 1 kg mass.
Mmin:
M
FN
1kg
T
T
FN
FF
FF
Fgx
Fgy
Fgy
Fgx
If M has the minimum amount of mass, then if you were to decrease it just a bit more the 1
kg mass would drag it up the incline. Friction is working with M to keep the 1 kg mass from
pulling M.