ASVAB Mechanical Comprehension Practice Test 811019 Results

Your Results Global Average
Questions 5 5
Correct 0 3.34
Score 0% 67%

Review

1

A wedge is most similar to what other type of simple machine?

70% Answer Correctly

third-class lever

second-class lever

inclined plane

first-class lever
Solution

The wedge is a moving inclined plane that is used to lift, hold, or break apart an object. A wedge converts force applied to its blunt end into force perpendicular to its inclined surface. In contrast to a stationary plane where force is applied to the object being moved, with a wedge the object is stationary and the force is being applied to the plane. Examples of a wedge include knives and chisels.

2

Collinear forces:

73% Answer Correctly

act in a common plane

act along the same line of action

pass through a common point

are unrelated to each other
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

Which of the following represents the force a surface exerts when an object presses against it?

49% Answer Correctly

mass

counter force

friction

normal force
Solution

Normal force (FN) represents the force a surface exerts when an object presses against it.

4

On Earth, acceleration due to gravity (g) is approximately __________. 

82% Answer Correctly

1 m/s

6.67 x 10-11 m/s2

1 m/s2

9.8 m/s2
Solution

Newton's Law of Univeral Gravitation defines the general formula for the attraction of gravity between two objects:  \(\vec{F_{g}} = { Gm_{1}m_{2} \over r^2}\) . In the specific case of an object falling toward Earth, the acceleration due to gravity (g) is approximately 9.8 m/s2. 

5 If the green box weighs 40 lbs. and 35 lbs. of force is applied 1 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
0.29 ft.
0.22 ft.
1.75 ft.
0.88 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 = \( \frac{R_bd_b}{R_a} \) = \( \frac{35 lbs. \times 1 ft.}{40 lbs.} \) = \( \frac{35 ft⋅lb}{40 lbs.} \) = 0.88 ft.