ASVAB Mechanical Comprehension Practice Test 718952 Results

Your Results Global Average
Questions 5 5
Correct 0 2.92
Score 0% 58%

Review

1

Which of the following is the formula for hydraulic pressure?

58% Answer Correctly

P = F/A2

P = FA2

P = FA

P = F/A
Solution

Hydraulics is the transmission of force through the use of liquids. Liquids are especially suited for transferring force in complex machines because they compress very little and can occupy very small spaces. Hydraulic pressure is calculated by dividing force by the area over which it is applied: P = F/A where F is force in pounds, A is area in square inches, and the resulting pressure is in pounds per square inch (psi).

2

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

38% Answer Correctly

driver gear

idler gear

output gear

driven 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.

3

If the handles of a wheelbarrow are 3 ft. from the wheel axle, what force must you exert to lift the handles if it's carrying a 270 lb. load concentrated at a point 0.5 ft. from the axle?

56% Answer Correctly

0.83 lbs

45 lbs

810 lbs

90 lbs
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. Plugging in the variables from this problem yields:

Fe x 3 ft. = 270 lbs x 0.5 ft
Fe = 135 ft-lb. / 3 ft 
Fe = 45 lbs

4 If you lift a 48 lbs. rock 23 ft. from the ground, how much work have you done?
71% Answer Correctly
552 ft⋅lb
2 ft⋅lb
1104 ft⋅lb
0 ft⋅lb
Solution
Work is force times distance. In this case, the force is the weight of the rock so:
\( W = F \times d \)
\( W = 48 \times 23 \)
\( W = 1104 \)
5 If the green arrow in this diagram represents 180 ft⋅lb of work, how far will the box move if it weighs 60 pounds?
73% Answer Correctly
30 ft.
20 ft.
120 ft.
3 ft.
Solution
The Law of Work states that the work put into a machine is equal to the work received from the machine under ideal conditions. In equation form, that's:

Win = Wout
Feffort x deffort = Fresistance x dresistance

In this problem, the effort work is 180 ft⋅lb and the resistance force is 60 lbs. and we need to calculate the resistance distance:

Win = Fresistance x dresistance
180 ft⋅lb = 60 lbs. x dresistance
dresistance = \( \frac{180ft⋅lb}{60 lbs.} \) = 3 ft.