ASVAB Mechanical Comprehension Practice Test 646321 Results

Your Results Global Average
Questions 5 5
Correct 0 2.88
Score 0% 58%

Review

1 If A = 7 ft. and the green box weighs 20 lbs. what is the torque acting on the A side of this lever?
75% Answer Correctly
70 ft⋅lb
140 ft⋅lb
420 ft⋅lb
560 ft⋅lb

Solution
For a lever, torque is weight x distance from the fulcrum which, in this case, is: 20 ft. x 7 lbs. = 140 ft⋅lb

2

The mechanical advantage of a wheel and axle is equal to the:

61% Answer Correctly

length of the axle

ratio of the diameters of the wheels

difference in the lengths of the axles

difference in the diameters of the wheels


Solution

A wheel and axle uses two different diameter wheels mounted to a connecting axle. Force is applied to the larger wheel and large movements of this wheel result in small movements in the smaller wheel. Because a larger movement distance is being translated to a smaller distance, force is increased with a mechanical advantage equal to the ratio of the diameters of the wheels. An example of a wheel and axle is the steering wheel of a car.


3

Which of the following is not true of a  first-class lever?

51% Answer Correctly

increases force

decreases distance

increases distance

changes the direction of 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.


4

The advantage of using a third-class lever is that it increases:

37% Answer Correctly

the mechanical advantage of the lever

the speed of the load

the distance traveled by the load

the force applied to the load


Solution

A third-class lever is used to increase distance traveled by an object in the same direction as the force applied. The fulcrum is at one end of the lever, the object at the other, and the force is applied between them. This lever does not impart a mechanical advantage as the effort force must be greater than the load but does impart extra speed to the load. Examples of third-class levers are shovels and tweezers.


5

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.