ASVAB Mechanical Comprehension Practice Test 633893 Results

Your Results Global Average
Questions 5 5
Correct 0 2.82
Score 0% 56%

Review

1

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

48% Answer Correctly

mass

normal force

friction

counter force


Solution

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


2 If the green box weighs 25 lbs. and is 5 ft. from the fulcrum, how far from the fulcrum would a 15 lbs. force need to be applied to balance the lever?
58% Answer Correctly
4.17 ft.
33.33 ft.
25 ft.
8.33 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 db, our missing value, and plugging in our variables yields:

db = \( \frac{R_ad_a}{R_b} \) = \( \frac{25 lbs. \times 5 ft.}{15 lbs.} \) = \( \frac{125 ft⋅lb}{15 lbs.} \) = 8.33 ft.


3

Two gears are connected and the smaller gear drives the larger gear. The speed of rotation will __________ and the torque will __________.

61% Answer Correctly

increase, decrease

decrease, decrease

increase, increase

decrease, increase


Solution

Connected gears of different numbers of teeth are used together to change the rotational speed and torque of the input force. If the smaller gear drives the larger gear, the speed of rotation will be reduced and the torque will increase. If the larger gear drives the smaller gear, the speed of rotation will increase and the torque will be reduced.


4

What type of load creates different stresses at different locations on a structure?

60% Answer Correctly

impact load

static uniformly distributed load

dynamic load

non-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 A mass of air has a pressure of 15.0 psi and a volume of 75 ft.3. If the air is compressed to a new volume of 70 ft.3, what is the new pressure?
56% Answer Correctly
32.1 psi
17.7 psi
16.1 psi
22.1 psi

Solution

According to Boyle's Law, pressure and volume are inversely proportional:

\( \frac{P_1}{P_2} \) = \( \frac{V_2}{V_1} \)

In this problem, V2 = 70 ft.3, V1 = 75 ft.3 and P1 = 15.0 psi. Solving for P2:

P2 = \( \frac{P_1}{\frac{V_2}{V_1}} \) = \( \frac{15.0 psi}{\frac{70 ft.^3}{75 ft.^3}} \) = 16.1 psi