This section of the U.S. Army's SIFT (Selection Instrument for Flight Training) exam tests your knowledge of basic physics, electrical, and mechanical theories.

Mechanical Comprehension questions focus on topics such as force, friction, current, fluid, pressure, pulleys, gears, screws, engines, and other machine operations.  You must familiarize yourself with physics, basic electronics, and mechanics concepts.

SIFT Mechanical Comprehension Practice Test

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25 Questions

1. An increase in mechanical advantage with a set motion for the load and a set applied force necessitates an increase in _______ the applied force?

the angle of action ofthe potential energy behindthe distance traveled by

2. A pendulum swings back and forth once per second. The pendulum is shortened by removing half of the string. The new frequency is 1.4 Hz (Hz=1/sec). How often will the pendulum swing back and forth in a minute?

728492

3. Adding salt to water raises its density. Will salt water have a lower, higher, or the same specific gravity than 1?

the samehigherlower

4. Which of the following is an example of convective heat transfer?

a man gets a sun burna man burns his hand on a hot pota man burns his hand in steam

5. A vacuum tank is held by weights at a depth of 50 feet underwater. If the tank is raised to a depth of 25 feet, will the pressure on the walls of the tank increase, decrease, or stay the same?

decreaseincreasestay the same

6. A ball is pushed down into a vertical spring. The ball is released and flies upward. Which best describes the states of energy the ball underwent?

kinetic energy to potential energypotential energy to kinetic energyconvective energy to potential energy

7. A cannon fires off a ship up towards a mountain range. Neglecting air resistance, where will the velocity of the projectile be greatest?

As it impacts the mountainsHalfway to the mountainsExiting the muzzle

8. Which of the following is true of this circuit?

there is no currentthe current is the same everywherethe voltage is the same everywhere

9. If Gear A is traveling at 10 rpm, how many times will Gear C rotate in 3 minutes?

30 times3 times1.7 times

10. Which of the following is the electrical component which holds a voltage across a gap between two conductive materials?

inductorresistorcapacitor

11. A ball is thrown horizontally off a cliff at the same time that an identical ball is dropped off a cliff. How long after the dropped ball hits the ground will the thrown ball hit?

approximately 1 second afterapproximately 2 seconds afterthey will hit at the same time

12. A windlass drum has two sections with different circumferences. When winding the drum, one side of the rope winds around the large section and the other unwinds from the small section. If the large section of the drum has a circumference of 3.5 ft and the other section has a circumference of 1 ft, how far will the weight lift with two full turns of the drum?

2.5 feet9 feet4.5 feet

13. Which of the following are not ways to increase the torque applied to a wrench?

increase the forceangle the force toward the centerincrease the length from the center to the applied force

14. Which type of situation will lead to condensation on the outside of pipes?

cold liquid in the pipe and hot air outside the pipehot liquid in the pipe and cold air outside the pipecold liquid in the pipe and colder air outside the pipe

15. Which color will absorb the most radiation?

blackgreendark yellow

16. Two gears (30 and 18 teeth) mesh. If the smaller gear rotates 3 times, how many times will the larger gear rotate?

1.6 times1.8 times3 times

17. River water enters a section where the water spreads out into a wide, deep area. Is the water likely to speed up, slow down, or remain at a constant speed?

remain at a constant speedspeed upslow down

18. If the resistors in the circuits are identical, which circuit will have the greatest overall resistance?

circuit Acircuit Bcircuit A and B have the same overall resistance

19. These pulleys are connected by belts. Which pulley travels the fastest?

Pulley APulley CPulley B

20. A wing in flight has a set of pressures causing the overall forces on the top and bottom of the wing. Where will the total force on the wing point?

up and to the leftup and to the rightneither A or B

21. Which device does not measure current in an electrical system?

ammetervoltmetermultimeter

22. Which orientation will require more force to pull?

with the rope parallel to the tableboth orientations are equalwith the rope at an angle to the table

23. Two identical pistons are connected by a pipe. What is the mechanical advantage of the piston system?

210.5

24. Which of these wrenches is likely to provide the greatest torque with a set force?

wrench Aboth wrenches will provide the same torquewrench B

25. Where should the fulcrum be located to balance this beam?

closer to the small masscloser to the large massexactly between the two masses