ASVAB Mechanical Comprehension Practice Test 271696 Results

Your Results Global Average
Questions 5 5
Correct 0 3.33
Score 0% 67%

Review

1

The measure of how much of the power put into a machine is turned into movement or force is called:

56% Answer Correctly

force multiplication

power

mechanical advantage

efficiency
Solution

The efficiency of a machine describes how much of the power put into the machine is turned into movement or force. A 100% efficient machine would turn all of the input power into output movement or force. However, no machine is 100% efficient due to friction, heat, wear and other imperfections that consume input power without delivering any output.

2 The green box weighs 70 lbs. and a 30 lbs. weight is placed 1 ft. from the fulcrum at the blue arrow. How far from the fulcrum would the green box need to be placed to balance the lever?
57% Answer Correctly
0.11 ft.
0.43 ft.
1.71 ft.
0 ft.
Solution

To balance this lever the torques on each side of the fulcrum must be equal. Torque is weight x distance from the fulcrum so the equation for equilibrium is:

Rada = Rbdb

where a represents the left side of the fulcrum and b the right, R is resistance (weight) and d is the distance from the fulcrum.

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

da = \( \frac{R_bd_b}{R_a} \) = \( \frac{30 lbs. \times 1 ft.}{70 lbs.} \) = \( \frac{30 ft⋅lb}{70 lbs.} \) = 0.43 ft.

3

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

84% Answer Correctly

wedge

first-class lever

inclined plane

none of these
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.

4

What defines the mechanical advantage of a first class lever?

65% Answer Correctly

position of the fulcrum

output force 

output distance

input force
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.

5

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

70% Answer Correctly

weight

density

potential energy

mass
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.