ASVAB Mechanical Comprehension Practice Test 612080 Results

Your Results Global Average
Questions 5 5
Correct 0 2.86
Score 0% 57%

Review

1

The force required to initally get an object moving is __________ the force required to keep it moving. 

76% Answer Correctly

lower than

the same as

opposite

higher than
Solution

For any given surface, the coefficient of static friction is higher than the coefficient of kinetic friction. More force is required to initally get an object moving than is required to keep it moving. Additionally, static friction only arises in response to an attempt to move an object (overcome the normal force between it and the surface).

2

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

40% Answer Correctly

lower than

the same as

higher than

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

Which of the following is not a type of structural load?

49% Answer Correctly

wind load

live load

dead load

occupancy load
Solution

Dead load is the weight of the building and materials, live load is additional weight due to occupancy or use, snow load is the weight of accumulated snow on a structure and wind load is the force of wind pressures against structure surfaces.

4 A = 6 ft., the green box weighs 15 lbs., and the blue box weighs 55 lbs. What does distance B need to be for this lever to balance?
65% Answer Correctly
0.55 ft.
0 ft.
9 ft.
1.64 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:

15 lbs. x 6 ft. = 55 lbs. x dB

dB = \( \frac{15 \times 6 ft⋅lb}{55 lbs.} \) = \( \frac{90 ft⋅lb}{55 lbs.} \) = 1.64 ft.

5 If the green box weighs 5 lbs. and 50 lbs. of force is applied 7 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 ft.
280 ft.
70 ft.
23.33 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 = \( \frac{R_bd_b}{R_a} \) = \( \frac{50 lbs. \times 7 ft.}{5 lbs.} \) = \( \frac{350 ft⋅lb}{5 lbs.} \) = 70 ft.