ASVAB Mechanical Comprehension Practice Test 332771 Results

	Your Results	Global Average
Questions	5	5
Correct	0	3.13
Score	0%	63%

Review

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

69% Answer Correctly

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

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.

2 What is the power output of a 4 hp engine that's 75% efficient?

40% Answer Correctly

	3300 \( \frac{ft⋅lb}{s} \)
	4950 \( \frac{ft⋅lb}{s} \)
	1650 \( \frac{ft⋅lb}{s} \)
	825 \( \frac{ft⋅lb}{s} \)

Solution

\( Efficiency = \frac{Power_{out}}{Power_{in}} \times 100 \)
Solving for power out: \( P_{o} = \frac{E \times P_{i}}{100} \)
Knowing that 1 hp = 550 \( \frac{ft⋅lb}{s} \), P_i becomes 4 hp x 550 \( \frac{ft⋅lb}{s} \) = 2200 \( \frac{ft⋅lb}{s} \)
\( P_{o} = \frac{E \times P_{i}}{100} = \frac{75 \times 2200 \frac{ft⋅lb}{s}}{100} \) \( = \frac{165000 \frac{ft⋅lb}{s}}{100} \) = 1650 \( \frac{ft⋅lb}{s} \)

The force exerted on an object due to gravity is called:

70% Answer Correctly

	mass
	weight
	potential energy
	density

Solution

Mass is an intrinsic property of matter and does not vary. Weight is the force exerted on the mass of an object due to gravity and a specific case of Newton's Second Law of Motion. Replace force with weight and acceleration with acceleration due to gravity on Earth (g) and the result is the formula for weight: W = mg or, substituting for g, weight equals mass multiplied by 9.8 m/s².

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

67% 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.

Two gears are connected and the larger gear drives the smaller gear. The speed of rotation will __________ and the torque will __________.

61% Answer Correctly

	decrease, decrease
	decrease, increase
	increase, decrease
	increase, increase

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.