ASVAB Mechanical Comprehension Practice Test 357255 Results

Your Results Global Average
Questions 5 5
Correct 0 2.79
Score 0% 56%

Review

1

A screw is most like which of the following other simple machines?

50% Answer Correctly

first-class lever

wheel and axle

block and tackle

inclined plane
Solution

A screw is an inclined plane wrapped in ridges (threads) around a cylinder. The distance between these ridges defines the pitch of the screw and this distance is how far the screw advances when it is turned once. The mechanical advantage of a screw is its circumference divided by the pitch.

2

What is the first step to solving a problem where multiple forces are acting on an object?

61% Answer Correctly

calculate the net force

calculate the total force

calculate potential energy

calculate kinetic energy
Solution

In mechanics, multiple forces are often acting on a particular object and, taken together, produce the net force acting on that object. Like force, net force is a vector quantity in that it has magnitude and direction.

3 If the handles of a wheelbarrow are 2.5 ft. from the wheel axle, how many pounds of force must you exert to lift the handles if it's carrying a 100 lbs. load concentrated at a point 0.5 ft. from the axle?
52% Answer Correctly
80
19.5
20
0.1
Solution
This problem describes a second-class lever and, for a second class lever, the effort force multiplied by the effort distance equals the resistance force multipied by the resistance distance: Fede = Frdr. In this problem we're looking for effort force:
\( F_e = \frac{F_r d_r}{d_e} \)
\( F_e = \frac{100 \times 0.5}{2.5} \)
\( F_e = \frac{50.0}{2.5} \)
\( F_e = 20 \)
4

Which of the following will increase the mechanical advantage of a second-class lever?

55% Answer Correctly

decrease the length of the lever

move the fulcrum between the force and the object being lifted

move the object being lifted farther away from the fulcrum

move the object being lifted closer to the fulcrum
Solution

A second-class lever is used to increase force on an object in the same direction as the force is applied. This lever requires a smaller force to lift a larger load but the force must be applied over a greater distance. The fulcrum is placed at one end of the lever and mechanical advantage increases as the object being lifted is moved closer to the fulcrum or the length of the lever is increased. An example of a second-class lever is a wheelbarrow.

5

What's the first gear in a gear train called?

57% Answer Correctly

input gear

driven gear

driver gear

idler gear
Solution

A gear train is two or more gears linked together. Gear trains are designed to increase or reduce the speed or torque outpout of a rotating system or change the direction of its output. The first gear in the chain is called the driver and the last gear in the chain the driven gear with the gears between them called idler gears.