ASVAB Mechanical Comprehension Practice Test 193072 Results

Your Results Global Average
Questions 5 5
Correct 0 3.36
Score 0% 67%

Review

1 What's the mechanical advantage of a wedge that's 2 inches wide and 16 inches long?
83% Answer Correctly
5
2
16
8
Solution

The mechanical advantage (MA) of a wedge is its length divided by its thickness:

MA = \( \frac{l}{t} \) = \( \frac{16 in.}{2 in.} \) = 8

2 How much work can a 3 hp engine do in 5 seconds?
53% Answer Correctly
8250 ft⋅lb
0 ft⋅lb
1 ft⋅lb
6 ft⋅lb
Solution
Horsepower (hp) is a common measure of power output for complex machines. By definition, a 1 hp machine does 550 ft⋅lb of work in 1 second: 1 hp = 550 ft⋅lb/s. Substituting the variables for this problem gives us:
\( W = 3 hp \times 550 \frac{ft⋅lb}{s} \times 5s = 8250 ft⋅lb \)
3

A fixed pulley has a mechanical advantage of:

68% Answer Correctly

2

0

1

-1
Solution

A fixed pulley is used to change the direction of a force and does not multiply the force applied. As such, it has a mechanical advantage of one. The benefit of a fixed pulley is that it can allow the force to be applied at a more convenient angle, for example, pulling downward or horizontally to lift an object instead of upward.

4

Which of the following represents how much two materials resist sliding across each other?

54% Answer Correctly

normal friction

coefficient of friction

static friction

kinetic friction
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 How much resistance could a 225 lb. effort force lift using a block and tackle pulley that has 10 ropes supporting the resistance?
81% Answer Correctly
2250 lbs.
4500 lbs.
2251.5 lbs.
2253 lbs.
Solution

The mechanical advantage (MA) of a block and tackle pulley is equal to the number of times the effort force changes direction. An easy way to count how many times the effort force changes direction is to count the number of ropes that support the resistance which, in this problem, is 10. With a MA of 10, a 225 lbs. effort force could lift 225 lbs. x 10 = 2250 lbs. resistance.