ASVAB Mechanical Comprehension Practice Test 346522 Results

Your Results Global Average
Questions 5 5
Correct 0 2.91
Score 0% 58%

Review

1 If the green box weighs 60 lbs. and is 7 ft. from the fulcrum, how much weight would need to be placed at the blue arrow to balance the lever if the arrow's distance from the fulcrum is 8 ft.?
63% Answer Correctly
105 lbs.
52.5 lbs.
480 lbs.
210 lbs.
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 Rb, our missing value, and plugging in our variables yields:

Rb = \( \frac{R_ad_a}{d_b} \) = \( \frac{60 lbs. \times 7 ft.}{8 ft.} \) = \( \frac{420 ft⋅lb}{8 ft.} \) = 52.5 lbs.

2

Force of friction due to kinetic friction is __________ the force of friction due to static friction.

40% Answer Correctly

higher than

lower than

the same as

opposite
Solution

The formula for force of friction (Ff) is the same whether kinetic or static friction applies: Ff = μFN. To distinguish between kinetic and static friction, μk and μs are often used in place of μ.

3 If a 5 lbs. weight is placed 9 ft. from the fulcrum at the blue arrow and the green box is 2 ft. from the fulcrum, how much would the green box have to weigh to balance the lever?
61% Answer Correctly
5.63 lbs.
90 lbs.
11.25 lbs.
22.5 lbs.
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 Ra, our missing value, and plugging in our variables yields:

Ra = \( \frac{R_bd_b}{d_a} \) = \( \frac{5 lbs. \times 9 ft.}{2 ft.} \) = \( \frac{45 ft⋅lb}{2 ft.} \) = 22.5 lbs.

4

What type of load doesn't create specific stress points or vary with time?

60% Answer Correctly

non-uniformly distributed load

impact load

concentrated load

static uniformly distributed 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

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

69% Answer Correctly

concentrated load

impact load

non-uniformly distributed load

dynamic 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.