ASVAB Mechanical Comprehension Practice Test 90661 Results

Your Results Global Average
Questions 5 5
Correct 0 3.56
Score 0% 71%

Review

1

A block and tackle with four pulleys would have a mechanical advantage of:

79% Answer Correctly

2

1

4

0
Solution

Two or more pulleys used together constitute a block and tackle which, unlike a fixed pulley, does impart mechanical advantage as a function of the number of pulleys that make up the arrangement.  So, for example, a block and tackle with three pulleys would have a mechanical advantage of three.

2

Two or more pulleys used together are called:

71% Answer Correctly

block and tackle

gears

third-class lever

wheel and axle
Solution

Two or more pulleys used together constitute a block and tackle which, unlike a fixed pulley, does impart mechanical advantage as a function of the number of pulleys that make up the arrangement.  So, for example, a block and tackle with three pulleys would have a mechanical advantage of three.

3 If input effort is 200 ft⋅lb, what output effort will be produced by a machine with a mechanical advantage of 2?
79% Answer Correctly
200ft⋅lb
0ft⋅lb
400 ft⋅lb
1600ft⋅lb
Solution
Mechanical advantage is the ratio of output force to input force and tells us by how many times a machine multiplies input effort. So, a machine with a mechanical advantage of 2 will multiply an input effort of 200 ft⋅lb by 2 to produce an output effort of 400 ft⋅lb.
4 What is the mechanical advantage of this inclined plane if the length of the ramp is 6 ft. and the height of the green box is 1 ft.?
82% Answer Correctly
7.5
8
6
12
Solution

The mechanical advantage (MA) of an inclined plane is the effort distance divided by the resistance distance. In this case, the effort distance is the length of the ramp and the resistance distance is the height of the green box:

MA = \( \frac{d_e}{d_r} \) = \( \frac{6 ft.}{1 ft.} \) = 6

5 If A = 11 ft., B = 2 ft., C = 10 ft., the green box weighs 30 lbs. and the blue box weighs 35 lbs., what does the orange box have to weigh for this lever to balance?
43% Answer Correctly
330 lbs.
104 lbs.
26 lbs.
60 lbs.
Solution
In order for this lever to balance, the torque acting on each side of the fulrum must be equal. So, the torque produced by A must equal the torque produced by B and C. Torque is weight x distance from the fulcrum which means that the following must be true for the lever to balance:

fAdA = fBdB + fCdC

For this problem, this equation becomes:

30 lbs. x 11 ft. = 35 lbs. x 2 ft. + fC x 10 ft.

330 ft. lbs. = 70 ft. lbs. + fC x 10 ft.

fC = \( \frac{330 ft. lbs. - 70 ft. lbs.}{10 ft.} \) = \( \frac{260 ft. lbs.}{10 ft.} \) = 26 lbs.