ASVAB Mechanical Comprehension Practice Test 960343 Results

	Your Results	Global Average
Questions	5	5
Correct	0	3.43
Score	0%	69%

Review

1 If the green arrow in this diagram represents 320 ft⋅lb of work, how far will the box move if it weighs 160 pounds?

72% Answer Correctly

	40 ft.
	0 ft.
	2 ft.
	8 ft.

Solution

The Law of Work states that the work put into a machine is equal to the work received from the machine under ideal conditions. In equation form, that's:

W_in = W_out
F_effort x d_effort = F_resistance x d_resistance

In this problem, the effort work is 320 ft⋅lb and the resistance force is 160 lbs. and we need to calculate the resistance distance:

W_in = F_resistance x d_resistance
320 ft⋅lb = 160 lbs. x d_resistance
d_resistance = \( \frac{320ft⋅lb}{160 lbs.} \) = 2 ft.

Which of these will have the most impact on the kinetic energy of an object?

54% Answer Correctly

	its weight
	its mass
	its direction
	its speed

Solution

Kinetic energy is the energy of movement and is a function of the mass of an object and its speed: \(KE = {1 \over 2}mv^2\) where m is mass in kilograms, v is speed in meters per second, and KE is in joules. The most impactful quantity to kinetic energy is velocity as an increase in mass increases KE linearly while an increase in speed increases KE exponentially.

What defines the mechanical advantage of a first class lever?

65% Answer Correctly

	output distance
	output force
	input force
	position of the fulcrum

Solution

A first-class lever is used to increase force or distance while changing the direction of the force. The lever pivots on a fulcrum and, when a force is applied to the lever at one side of the fulcrum, the other end moves in the opposite direction. The position of the fulcrum also defines the mechanical advantage of the lever. If the fulcrum is closer to the force being applied, the load can be moved a greater distance at the expense of requiring a greater input force. If the fulcrum is closer to the load, less force is required but the force must be applied over a longer distance. An example of a first-class lever is a seesaw / teeter-totter.

A a seesaw / teeter-totter is an example of which of the following?

69% Answer Correctly

	second-class lever
	inclined plane
	first-class lever
	third-class lever

Solution

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

84% Answer Correctly

	none of these
	inclined plane
	wedge
	first-class lever

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.