ASVAB Mechanical Comprehension Practice Test 688886 Results

Your Results Global Average
Questions 5 5
Correct 0 3.65
Score 0% 73%

Review

1

Specific gravity is a comparison of the density of an object with the density of:

57% Answer Correctly

carbon

water

air

oil
Solution

Specific gravity is the ratio of the density of equal volumes of a substance and water and is measured by a hyrdometer.

2 What is the efficiency of a machine has work input of 65 ft⋅lb and work output of 48 ft⋅lb?
68% Answer Correctly
1%
75%
18%
37%
Solution
Due to friction, a machine will never be able to utilize 100% of its work input. A certain percentage of that input will be lost in overcoming friction within the machine. Effeciency is a measure of how much of a machine's work input can be turned into useful work output and is calculated by dividing work output by work input and multiplying the result by 100:
\( Efficiency = \frac{Work_{out}}{Work_{in}} \times 100 \) \( = \frac{48 ft⋅lb}{65 ft⋅lb} \times 100 \) \( = 75% \) %
3

Friction between two or more solid objects that are not moving relative to each other is called:

74% Answer Correctly

kinetic friction

static friction

dynamic friction

gravitational friction
Solution

Static friction is friction between two or more solid objects that are not moving relative to each other. An example is the friction that prevents a box on a sloped surface from sliding farther down the surface.

4

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

76% Answer Correctly

lower than

higher than

the same as

opposite
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).

5

The steering wheel of a car is an example of which type of simple machine?

89% Answer Correctly

wheel and axle

fixed pulley

first-class lever

block and tackle
Solution

A wheel and axle uses two different diameter wheels mounted to a connecting axle. Force is applied to the larger wheel and large movements of this wheel result in small movements in the smaller wheel. Because a larger movement distance is being translated to a smaller distance, force is increased with a mechanical advantage equal to the ratio of the diameters of the wheels. An example of a wheel and axle is the steering wheel of a car.