ASVAB Mechanical Comprehension Practice Test 521515 Results

Your Results Global Average
Questions 5 5
Correct 0 3.08
Score 0% 62%

Review

1

An inclined plane increases ___________ to reduce ____________.

58% Answer Correctly

force, distance

force, power

distance, power

distance, force


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.


2

Which of the following is not a modulus of elasticity?

47% Answer Correctly

stretch modulus

bulk modulus

shear modulus

stress modulus


Solution

The modulus of elasticity measures how much a material or structure will deflect under stress. Stretch modulus is longitudinal stretch (like stretching raw bread dough), shear modulus is longitudinal deflection (like the horizontal displacement of a stack of magzines when a heavy object is placed upon them), and bulk modulus is compression of volume (like the compression of a loaf of bread under a heavy can at the bottom of a grocery bag).


3

Which of the following is the formula for gravitational potential energy?

61% Answer Correctly

\(PE = { 1 \over 2} mg^2\)

\(PE = mgh\)

\(PE = { 1 \over 2} mv^2\)

\(PE = mg^2h\)


Solution

Gravitational potential energy is energy by virtue of gravity. The higher an object is raised above a surface the greater the distance it must fall to reach that surface and the more velocity it will build as it falls. For gravitational potential energy, PE = mgh where m is mass (kilograms), h is height (meters), and g is acceleration due to gravity which is a constant (9.8 m/s2).


4 What is the mechanical advantage of this inclined plane if the length of the ramp is 63 ft. and the height of the green box is 7 ft.?
82% Answer Correctly
11
0
9
3

Solution

The mechanical advantage (MA) of an inclined plane is the effort distance divided by the resistance distance. In this case, the effort distance is the length of the ramp and the resistance distance is the height of the green box:

MA = \( \frac{d_e}{d_r} \) = \( \frac{63 ft.}{7 ft.} \) = 9


5

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

61% Answer Correctly

decrease, increase

increase, decrease

decrease, 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.