ASVAB Mechanical Comprehension Practice Test 511442 Results

Your Results Global Average
Questions 5 5
Correct 0 3.04
Score 0% 61%

Review

1 If you lift a 34 lbs. rock 3 ft. from the ground, how much work have you done?
70% Answer Correctly
204 ft⋅lb
11 ft⋅lb
51 ft⋅lb
102 ft⋅lb
Solution
Work is force times distance. In this case, the force is the weight of the rock so:
\( W = F \times d \)
\( W = 34 \times 3 \)
\( W = 102 \)
2

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

58% Answer Correctly

lever

gear

pulley

screw
Solution

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

3 If the green box weighs 30 lbs. and 10 lbs. of force is applied 9 ft. from the fulcrum at the blue arrow, how far from the fulcrum would the green box need to be placed to balance the lever?
55% Answer Correctly
270 ft.
1 ft.
3 ft.
1.5 ft.
Solution

To balance this lever the torques at the green box and the blue arrow must be equal. Torque is weight x distance from the fulcrum so the equation for equilibrium is:

Rada = Rbdb

where a represents the green box and b the blue arrow, R is resistance (weight/force) and d is the distance from the fulcrum.

Solving for da, our missing value, and plugging in our variables yields:

da = \( \frac{R_bd_b}{R_a} \) = \( \frac{10 lbs. \times 9 ft.}{30 lbs.} \) = \( \frac{90 ft⋅lb}{30 lbs.} \) = 3 ft.

4 A = 7 ft., the green box weighs 10 lbs., and the blue box weighs 55 lbs. What does distance B need to be for this lever to balance?
65% Answer Correctly
0 ft.
70 ft.
2.55 ft.
1.27 ft.
Solution
In order for this lever to balance, the torque acting on side A must equal the torque acting on side B. Torque is weight x distance from the fulcrum which means that the following must be true for the lever to balance:

fAdA = fBdB

For this problem, the equation becomes:

10 lbs. x 7 ft. = 55 lbs. x dB

dB = \( \frac{10 \times 7 ft⋅lb}{55 lbs.} \) = \( \frac{70 ft⋅lb}{55 lbs.} \) = 1.27 ft.

5

The science that deals with motion and the forces that produce motion is called which of the following?

57% Answer Correctly

mechanics

aeronautics

engineering

physics
Solution

Mechanics deals with motion and the forces that produce motion.