ASVAB Mechanical Comprehension Practice Test 367919 Results

Your Results Global Average
Questions 5 5
Correct 0 3.15
Score 0% 63%

Review

1 The radius of the axle is 7, the radius of the wheel is 12, and the blue box weighs 25 lbs. What is the effort force necessary to balance the load?
53% Answer Correctly
14.62 lbs.
19 lbs.
12 lbs.
13.71 lbs.

Solution

The mechanical advantage of a wheel and axle is the input radius divided by the output radius:

MA = \( \frac{r_i}{r_o} \)

In this case, the input radius (where the effort force is being applied) is 12 and the output radius (where the resistance is being applied) is 7 for a mechanical advantage of \( \frac{12}{7} \) = 1.71

MA = \( \frac{load}{effort} \) so effort = \( \frac{load}{MA} \) = \( \frac{25 lbs.}{1.71} \) = 14.62 lbs.


2

What type of load varies with time or affects a structure that experiences a high degree of movement?

66% Answer Correctly

concentrated load

static load

impact 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.


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

decrease, decrease

increase, increase

increase, decrease

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 A 340 lb. barrel is rolled up a 6 ft. ramp to a platform that's 1 ft. tall. What effort is required to move the barrel?
53% Answer Correctly
85 lbs.
49.7 lbs.
18.9 lbs.
56.7 lbs.

Solution

This problem describes an inclined plane and, for an inclined plane, the effort force multiplied by the effort distance equals the resistance force multipied by the resistance distance:

Fede = Frdr

Plugging in the variables from this problem yields:

Fe x 6 ft. = 340 lbs. x 1 ft.
Fe = \( \frac{340 ft⋅lb}{6 ft.} \) = 56.7 lbs.


5 50 lbs. of effort is used by a machine to lift a 150 lbs. box. What is the mechanical advantage of the machine?
84% Answer Correctly
5
3
9
3.3

Solution

Mechanical advantage is resistance force divided by effort force:

MA = \( \frac{F_r}{F_e} \) = \( \frac{150 lbs.}{50 lbs.} \) = 3