ASVAB Mechanical Comprehension Practice Test 977867 Results

Your Results Global Average
Questions 5 5
Correct 0 3.30
Score 0% 66%

Review

1

A ramp is an example of which kind of simple machine?

84% Answer Correctly

none of these

inclined plane

first-class lever

wedge


Solution

An inclined plane is a simple machine that reduces the force needed to raise an object to a certain height. Work equals force x distance and, by increasing the distance that the object travels, an inclined plane reduces the force necessary to raise it to a particular height. In this case, the mechanical advantage is to make the task easier. An example of an inclined plane is a ramp.


2

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

77% Answer Correctly

marble

ice

steel

concrete


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.


3

Sam can do 50 ft. lb. of work in 2 minutes and 5 seconds. What would Sam have to do to increase his power output?

64% Answer Correctly

do the work in 2 minutes

do the work in 3 minutes

do 25 ft. lb. of work in 2 minutes 5 seconds

do 100 ft. lb. of work in 4 minutes 12 seconds


Solution

Power is the rate of doing work or \(\frac{W}{t}\). To increase power, increase the work being done in the same amount of time or do the same amount of work in less time.


4 If you have a gear train with three gears, the first with 22 teeth, the second with 20 teeth, and the third with 6 teeth, what is its mechanical advantage?
51% Answer Correctly
4
1.8
3.7
1.2

Solution

The mechanical advantage of a gear train is its gear ratio. The gear ratio (Vr) 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 three gears so the equation becomes:

Vr = \( \frac{N_1}{N_2} \) \( \frac{N_2}{N_3} \) = \( \frac{22}{20} \) \( \frac{20}{6} \) = \( \frac{22}{6} \) = 3.7


5

Which of these will have the most impact on the kinetic energy of an object?

54% Answer Correctly

its direction

its speed

its weight

its mass


Solution

Kinetic energy is the energy of movement and is a function of the mass of an object and its speed: \(KE = {1 \over 2}mv^2\) where m is mass in kilograms, v is speed in meters per second, and KE is in joules. The most impactful quantity to kinetic energy is velocity as an increase in mass increases KE linearly while an increase in speed increases KE exponentially.