ASVAB Mechanical Comprehension Practice Test 102072 Results

Your Results Global Average
Questions 5 5
Correct 0 2.47
Score 0% 49%

Review

1 If the handles of a wheelbarrow are 1.0 ft. from the wheel axle, how many pounds of force must you exert to lift the handles if it's carrying a 160 lbs. load concentrated at a point 1.5 ft. from the axle?
52% Answer Correctly
205.1
None of these is correct
160.3
240
Solution
This problem describes a second-class lever and, for a second class lever, the effort force multiplied by the effort distance equals the resistance force multipied by the resistance distance: Fede = Frdr. In this problem we're looking for effort force:
\( F_e = \frac{F_r d_r}{d_e} \)
\( F_e = \frac{160 \times 1.5}{1.0} \)
\( F_e = \frac{240.0}{1.0} \)
\( F_e = 240 \)
2

Which of the following is not a type of simple machine?

58% Answer Correctly

pulley

gear

lever

screw
Solution

The six types of simple machines are the lever, wheel and axle, pulley, inclined plane, wedge, and screw.

3

What's the last gear in a gear train called?

38% Answer Correctly

driven gear

driver gear

output gear

idler gear
Solution

A gear train is two or more gears linked together. Gear trains are designed to increase or reduce the speed or torque outpout of a rotating system or change the direction of its output. The first gear in the chain is called the driver and the last gear in the chain the driven gear with the gears between them called idler gears.

4

Which of the following is the formula for torque?

61% Answer Correctly

τ = F/r2

τ = rF

τ = r/F

τ = F/r
Solution

Torque measures force applied during rotation: τ = rF.  Torque (τ, the Greek letter tau) = the radius of the lever arm (r) multiplied by the force (F) applied. Radius is measured from the center of rotation or fulcrum to the point at which the perpendicular force is being applied. The resulting unit for torque is newton-meter (N-m) or foot-pound (ft-lb).

5

Force of friction due to kinetic friction is __________ the force of friction due to static friction.

40% Answer Correctly

the same as

opposite

higher than

lower than
Solution

The formula for force of friction (Ff) is the same whether kinetic or static friction applies: Ff = μFN. To distinguish between kinetic and static friction, μk and μs are often used in place of μ.