ASVAB Mechanical Comprehension Practice Test 263915 Results

Your Results Global Average
Questions 5 5
Correct 0 3.71
Score 0% 74%

Review

1 If the green arrow in this diagram represents 260 ft⋅lb of work, how far will the box move if it weighs 130 pounds?
72% Answer Correctly
520 ft.
2 ft.
32 ft.
1 ft.

Solution
The Law of Work states that the work put into a machine is equal to the work received from the machine under ideal conditions. In equation form, that's:

Win = Wout
Feffort x deffort = Fresistance x dresistance

In this problem, the effort work is 260 ft⋅lb and the resistance force is 130 lbs. and we need to calculate the resistance distance:

Win = Fresistance x dresistance
260 ft⋅lb = 130 lbs. x dresistance
dresistance = \( \frac{260ft⋅lb}{130 lbs.} \) = 2 ft.


2

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

81% Answer Correctly

9.8 m/s2

1 m/s2

1 m/s

6.67 x 10-11 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. 


3

What type of load acts on a relatively small area of a structure?

75% Answer Correctly

non-uniformly distributed load

dynamic load

impact load

concentrated 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.


4

Which of the following surfaces would have the highest coefficient of friction?

77% Answer Correctly

concrete

marble

steel

ice


Solution

Coefficient of friction (μ) represents how much two materials resist sliding across each other.  Smooth surfaces like ice have low coefficients of friction while rough surfaces like concrete have high μ.


5 If the green box weighs 30 lbs. and is 9 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
101.25 lbs.
135 lbs.
33.75 lbs.
240 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 = \( \frac{R_ad_a}{d_b} \) = \( \frac{30 lbs. \times 9 ft.}{8 ft.} \) = \( \frac{270 ft⋅lb}{8 ft.} \) = 33.75 lbs.