ASVAB Mechanical Comprehension Practice Test 734047 Results

Your Results Global Average
Questions 5 5
Correct 0 3.13
Score 0% 63%

Review

1 If you have a gear train with two gears, the first with 32 teeth and the second with 16 teeth, how many revolutions does the second gear make for each revolution of the first gear?
77% Answer Correctly
3
2
10
2.2
Solution

The gear ratio (Vr) of a gear train is the product of the gear ratios between the pairs of meshed gears. Let N represent the number of teeth for each gear:

Vr = \( \frac{N_1}{N_2} \) \( \frac{N_2}{N_3} \) \( \frac{N_3}{N_4} \) ... \( \frac{N_n}{N_{n+1}} \)

In this problem, we have only two gears so the equation becomes:

Vr = \( \frac{N_1}{N_2} \) = \( \frac{32}{16} \) = 2

2

The science that deals with motion and the forces that produce motion is called which of the following?

57% Answer Correctly

mechanics

aeronautics

engineering

physics
Solution

Mechanics deals with motion and the forces that produce motion.

3 What is the power output of a 8 hp engine that's 45% efficient?
40% Answer Correctly
990 \( \frac{ft⋅lb}{s} \)
3960 \( \frac{ft⋅lb}{s} \)
1980 \( \frac{ft⋅lb}{s} \)
7920 \( \frac{ft⋅lb}{s} \)
Solution
\( Efficiency = \frac{Power_{out}}{Power_{in}} \times 100 \)
Solving for power out: \( P_{o} = \frac{E \times P_{i}}{100} \)
Knowing that 1 hp = 550 \( \frac{ft⋅lb}{s} \), Pi becomes 8 hp x 550 \( \frac{ft⋅lb}{s} \) = 4400 \( \frac{ft⋅lb}{s} \)
\( P_{o} = \frac{E \times P_{i}}{100} = \frac{45 \times 4400 \frac{ft⋅lb}{s}}{100} \) \( = \frac{198000 \frac{ft⋅lb}{s}}{100} \) = 1980 \( \frac{ft⋅lb}{s} \)
4

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

85% Answer Correctly

tile

concrete

leather

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 How much work can a 7 hp engine do in 3 seconds?
52% Answer Correctly
14 ft⋅lb
3 ft⋅lb
0 ft⋅lb
11550 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:
\( W = 7 hp \times 550 \frac{ft⋅lb}{s} \times 3s = 11550 ft⋅lb \)