ASVAB Mechanical Comprehension Practice Test 950949 Results

Your Results Global Average
Questions 5 5
Correct 0 3.27
Score 0% 65%

Review

1 If the green box weighs 65 lbs. and is 9 ft. from the fulcrum, how far from the fulcrum would a 60 lbs. force need to be applied to balance the lever?
58% Answer Correctly
19.5 ft.
4.88 ft.
2.44 ft.
9.75 ft.

Solution

To balance this lever the torques at the green box and the blue arrow must be equal. Torque is weight x distance from the fulcrum so the equation for equilibrium is:

Rada = Rbdb

where a represents the green box and b the blue arrow, R is resistance (weight/force) and d is the distance from the fulcrum.

Solving for db, our missing value, and plugging in our variables yields:

db = \( \frac{R_ad_a}{R_b} \) = \( \frac{65 lbs. \times 9 ft.}{60 lbs.} \) = \( \frac{585 ft⋅lb}{60 lbs.} \) = 9.75 ft.


2

The force required to initally get an object moving is __________ the force required to keep it moving. 

76% Answer Correctly

higher than

opposite

lower than

the same as


Solution

For any given surface, the coefficient of static friction is higher than the coefficient of kinetic friction. More force is required to initally get an object moving than is required to keep it moving. Additionally, static friction only arises in response to an attempt to move an object (overcome the normal force between it and the surface).


3

Tension is a force that does which of the following?

75% Answer Correctly

heats up an object

compacts an object

stretches an object

slows an object


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.


4

Boyle's law defines the relationship between pressure and volume as:

57% Answer Correctly

\(\frac{P_1}{P_2} = \frac{V_2}{V_1}\)

\({P_1}{P_2} = {V_1}{V_2}\)

\(\frac{P_1}{P_2} = \frac{V_1}{V_2}\)

\(\frac{P_1}{P_2} = {V_1}{V_2}\)


Solution

Boyle's law states that "for a fixed amount of an ideal gas kept at a fixed temperature, pressure and volume are inversely proportional". Expressed as a formula, that's \(\frac{P_1}{P_2} = \frac{V_2}{V_1}\)


5

Coplanar forces:

62% Answer Correctly

act in a common plane

act along the same line of action

have opposite dimensions

pass through a common point


Solution

Collinear forces act along the same line of action, concurrent forces pass through a common point and coplanar forces act in a common plane.