ASVAB Mechanical Comprehension Practice Test 333176 Results

Your Results Global Average
Questions 5 5
Correct 0 3.49
Score 0% 70%

Review

1 If the green box weighs 25 lbs. and is 1 ft. from the fulcrum, how far from the fulcrum would a 65 lbs. weight need to be placed to balance the lever?
61% Answer Correctly
0.38 ft.
0.1 ft.
0.13 ft.
0.19 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 db, our missing value, and plugging in our variables yields:

db = \( \frac{R_ad_a}{R_b} \) = \( \frac{25 lbs. \times 1 ft.}{65 lbs.} \) = \( \frac{25 ft⋅lb}{65 lbs.} \) = 0.38 ft.


2 What is the mechanical advantage of this inclined plane if the length of the ramp is 16 ft. and the height of the green box is 2 ft.?
82% Answer Correctly
16
8
7.2
2

Solution

The mechanical advantage (MA) of an inclined plane is the effort distance divided by the resistance distance. In this case, the effort distance is the length of the ramp and the resistance distance is the height of the green box:

MA = \( \frac{d_e}{d_r} \) = \( \frac{16 ft.}{2 ft.} \) = 8


3

The force amplification achieved by using a tool, mechanical device or machine system is called:

80% Answer Correctly

efficiency

work

power

mechanical advantage


Solution

Mechanical advantage is a measure of the force amplification achieved by using a tool, mechanical device or machine system. Such a device utilizes input force and trades off forces against movement to amplify and/or change its direction.


4

What type of load is sudden and for a relatively short duration?

70% Answer Correctly

dynamic load

non-uniformly distributed load

concentrated load

impact load


Solution

A concentrated load acts on a relatively small area of a structure, a static uniformly distributed load doesn't create specific stress points or vary with time, a dynamic load varies with time or affects a structure that experiences a high degree of movement, an impact load is sudden and for a relatively short duration and a non-uniformly distributed load creates different stresses at different locations on a structure.


5

Which of the following will increase the mechanical advantage of a second-class lever?

56% Answer Correctly

decrease the length of the lever

move the object being lifted farther away from the fulcrum

move the object being lifted closer to the fulcrum

move the fulcrum between the force and the object being lifted


Solution

A second-class lever is used to increase force on an object in the same direction as the force is applied. This lever requires a smaller force to lift a larger load but the force must be applied over a greater distance. The fulcrum is placed at one end of the lever and mechanical advantage increases as the object being lifted is moved closer to the fulcrum or the length of the lever is increased. An example of a second-class lever is a wheelbarrow.