ASVAB Mechanical Comprehension Practice Test 702758 Results

Your Results Global Average
Questions 5 5
Correct 0 2.51
Score 0% 50%

Review

1 If you have a gear train with three gears, the first with 26 teeth, the second with 14 teeth, and the third with 4 teeth, what is its mechanical advantage?
51% Answer Correctly
9.5
12.5
19.5
6.5

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 = \( \frac{N_1}{N_2} \) \( \frac{N_2}{N_3} \) = \( \frac{26}{14} \) \( \frac{14}{4} \) = \( \frac{26}{4} \) = 6.5


2

Which of the following statements about this pulley configuration is false?

48% Answer Correctly

Mechanical advantage is the number of ropes that support the resistance

This is a block and tackle pulley configuration

Only multiplies the effort force

Changes the direction of and multiplies the effort force


Solution

A block and tackle is a combination of one or more fixed pulleys and one or more movable pulleys where the fixed pulleys change the direction of the effort force and the movable pulleys multiply it. The mechanical advantage is equal to the number of times the effort force changes direction and can be increased by adding more pulley wheels to the system. An easy way to find the mechanical advantage of a block and tackle pulley system is to count the number of ropes that support the resistance.


3

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

53% Answer Correctly

kinetic friction

normal friction

static friction

coefficient of 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.


4

A truck is using a rope to pull a car. Tension in the rope is greatest in which of the following places?

50% Answer Correctly

near the car

near the truck

in the middle

tension is equal in all parts of the rope


Solution

Tension is a force that stretches or elongates something. When a cable or rope is used to pull an object, for example, it stretches internally as it accepts the weight that it's moving. Although tension is often treated as applying equally to all parts of a material, it's greater at the places where the material is under the most stress.


5

Which of the following is not a type of structural load?

50% Answer Correctly

live load

occupancy load

dead load

wind load


Solution

Dead load is the weight of the building and materials, live load is additional weight due to occupancy or use, snow load is the weight of accumulated snow on a structure and wind load is the force of wind pressures against structure surfaces.