Sample Advanced Section Exam
1) An airplane is flying in level flight and steady speed. It weighs 250,000 lbf. It is
powered by two jet engines, one under each wing. Each engine delivers 10,000 lbf. of
thrust.
a) draw a free-body diagram showing the forces acting on the airplane
b) what is the Lift force acting on the airplane?
c) what is the Drag force acting on the airplane?
2) A diver stands on a diving board ready to jump into the swimming pool. He weighs 40
kg.
a) Draw a diagram of the forces and moments (torques) acting on the diving
board
b) What is the magnitude and direction of the moment (or torque) acting at point
A.
(you can ignore the weight of the board)
30o
60o
B
C
A
1 Kg
3) A lead brick of mass 1 Kg is suspended from the ceiling by three thin wires, as shown
in the diagram above.
a) what is the tension in each string, A
b) what is the tension in strings B and C?
c) What is the total force acting at each of the attachment points on the ceiling?
4) Mickey mouse, weighing in at 10 Kg, (that’s some mouse!) stands on a see-saw as
shown. On the other end, at the tip of the see-saw, is a pile of cheese weighing 4 Kg.
What position must Mickey stand at in order to avoid tipping the see-saw? (you can
ignore the weight of the see-saw)
A
5) A Rollercoaster car is running down the track. At the position shown it has reached a
speed of 20 meters/second.
a) how fast will it be going when it reaches the bottom of the loop (point A)
which lies 20 meters below the current position of the car.
b) How how can it go on the track before the speed goes to zero and the car starts
to fall back?
Θ
6) A brick weighing 5 lbf lies on a table. The coefficient of static friction between the
brick and the table is 0.3. What is the angle, Θ, to which the table must be raised to get
the brick to start sliding?