ASVAB Mechanical Comprehension Practice Test 698140 Results

	Your Results	Global Average
Questions	5	5
Correct	0	3.57
Score	0%	71%

Review

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

76% Answer Correctly

	higher than
	lower 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).

On Earth, acceleration due to gravity (g) is approximately __________.

81% Answer Correctly

	6.67 x 10^-11 m/s²
	1 m/s
	9.8 m/s²
	1 m/s²

Solution

Newton's Law of Univeral Gravitation defines the general formula for the attraction of gravity between two objects: \(\vec{F_{g}} = { Gm_{1}m_{2} \over r^2}\) . In the specific case of an object falling toward Earth, the acceleration due to gravity (g) is approximately 9.8 m/s².

Connected gears of different numbers of teeth are used together to change which of the following charasteristics of the input force?

65% Answer Correctly

	torque
	rotational direction
	force
	energy

Solution

Connected gears of different numbers of teeth are used together to change the rotational speed and torque of the input force. If the smaller gear drives the larger gear, the speed of rotation will be reduced and the torque will increase. If the larger gear drives the smaller gear, the speed of rotation will increase and the torque will be reduced.

4 What is the efficiency of a machine has work input of 115 ft⋅lb and work output of 103 ft⋅lb?

67% Answer Correctly

	90%
	45%
	180%
	360%

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:
\( Efficiency = \frac{Work_{out}}{Work_{in}} \times 100 \) \( = \frac{103 ft⋅lb}{115 ft⋅lb} \times 100 \) \( = 90% \) %

The mass of an object correlates to the size of the object but ultimately depends on:

66% Answer Correctly

	gravity
	the object's potential energy
	the object's density
	the object's weight

Solution

Mass is a measure of the amount of matter in an object. In general, larger objects have larger mass than smaller objects but mass ultimately depends on how compact (dense) a substance is.