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. 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

2. 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

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

capacitorresistorinductor

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

a man burns his hand in steama man burns his hand on a hot pota man gets a sun burn

5. The cam rotates at 5 rpm. How many times will the follower (needle) move up and down in a minute?

1407220

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

0.512

7. The larger piston has four times as much horizontal area as the smaller piston. If the small piston is compressed 8 inches, how far will the larger piston move?

2 inches32 inches8 inches

8. A ball is thrown straight into the air with an initial kinetic energy of 100 ft-lb. What is the potential energy of the ball at half of the height of the flight path?

66 ft-lb33 ft-lb50 ft-lb

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

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

10. A magnet is placed in the middle of two identical, anchored magnets. Which direction will the magnet go?

towards magnet 2the magnet won’t movetowards magnet 1

11. 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?

9 feet4.5 feet2.5 feet

12. Which orientation will require more force to pull?

with the rope parallel to the tablewith the rope at an angle to the tableboth orientations are equal

13. 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?

they will hit at the same timeapproximately 2 seconds afterapproximately 1 second after

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

the samelowerhigher

15. 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?

neither A or Bup and to the leftup and to the right

16. 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?

convective energy to potential energykinetic energy to potential energypotential energy to kinetic energy

17. 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?

stay the sameincreasedecrease

18. 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

19. Which color will absorb the most radiation?

dark yellowgreenblack

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

exactly between the two massescloser to the small masscloser to the large mass

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

the voltage is the same everywherethe current is the same everywherethere is no current

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

multimeterammetervoltmeter

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

Pulley APulley BPulley C

24. A solid substance melts at -21°C. If the object is known to change phase at 81°C, will the object be a solid, liquid, or gas at 90°C?

liquidsolidgas

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

both wrenches will provide the same torquewrench Awrench B