ASVAB Mechanical Comprehension Practice Test 293910 Results

Your Results Global Average
Questions 5 5
Correct 0 3.29
Score 0% 66%

Review

1

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

do the work in 3 minutes

do the work in 2 minutes

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


2

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

85% Answer Correctly

none of these

first-class lever

inclined plane

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.


3

Which of the following is the formula for hydraulic pressure?

58% Answer Correctly

P = FA2

P = FA

P = F/A2

P = F/A


Solution

Hydraulics is the transmission of force through the use of liquids. Liquids are especially suited for transferring force in complex machines because they compress very little and can occupy very small spaces. Hydraulic pressure is calculated by dividing force by the area over which it is applied: P = F/A where F is force in pounds, A is area in square inches, and the resulting pressure is in pounds per square inch (psi).


4

The force exerted on an object due to gravity is called:

70% Answer Correctly

potential energy

weight

density

mass


Solution

Mass is an intrinsic property of matter and does not vary. Weight is the force exerted on the mass of an object due to gravity and a specific case of Newton's Second Law of Motion. Replace force with weight and acceleration with acceleration due to gravity on Earth (g) and the result is the formula for weight: W = mg or, substituting for g, weight equals mass multiplied by 9.8 m/s2.


5 If you have a gear train with three gears, the first with 22 teeth, the second with 12 teeth, and the third with 4 teeth, what is its mechanical advantage?
51% Answer Correctly
5.5
7
8.5
6.1

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 = \( \frac{N_1}{N_2} \) \( \frac{N_2}{N_3} \) = \( \frac{22}{12} \) \( \frac{12}{4} \) = \( \frac{22}{4} \) = 5.5