ASVAB Mechanical Comprehension Practice Test 526030 Results

Your Results Global Average
Questions 5 5
Correct 0 2.97
Score 0% 59%

Review

1

Which of the following statements about drag is false?

58% Answer Correctly

the amount of drag depends on the speed of an object

drag occurs during movement through a fluid

slower objects experience more drag than faster objects

the amount of drag depends on the shape of an object
Solution

Drag is friction that opposes movement through a fluid like liquid or air. The amount of drag depends on the shape and speed of the object with slower objects experiencing less drag than faster objects and more aerodynamic objects experiencing less drag than those with a large leading surface area.

2

Concurrent forces:

55% Answer Correctly

act in a common plane

act in a common dimension

pass through a common point

act along the same line of action
Solution

Collinear forces act along the same line of action, concurrent forces pass through a common point and coplanar forces act in a common plane.

3 If the handles of a wheelbarrow are 0.5 ft. from the wheel axle, how many pounds of force must you exert to lift the handles if it's carrying a 240 lbs. load concentrated at a point 1.0 ft. from the axle?
52% Answer Correctly
-28
480
250.6
None of these is correct
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:
\( F_e = \frac{F_r d_r}{d_e} \)
\( F_e = \frac{240 \times 1.0}{0.5} \)
\( F_e = \frac{240.0}{0.5} \)
\( F_e = 480 \)
4

Hydraulics is the transmission of force through the use of which of the following?

73% Answer Correctly

air pressure

gear systems

torque

liquids
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).

5 The green box weighs 20 lbs. and a 40 lbs. weight is placed 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?
57% Answer Correctly
54 ft.
18 ft.
0 ft.
72 ft.
Solution

To balance this lever the torques on each side of the fulcrum must be equal. Torque is weight x distance from the fulcrum so the equation for equilibrium is:

Rada = Rbdb

where a represents the left side of the fulcrum and b the right, R is resistance (weight) and d is the distance from the fulcrum.

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

da = \( \frac{R_bd_b}{R_a} \) = \( \frac{40 lbs. \times 9 ft.}{20 lbs.} \) = \( \frac{360 ft⋅lb}{20 lbs.} \) = 18 ft.