ASVAB Mechanical Comprehension Practice Test 615810 Results

	Your Results	Global Average
Questions	5	5
Correct	0	3.36
Score	0%	67%

Review

Which class of lever is used to increase force on an object in the same direction as the force is applied?

53% Answer Correctly

	second
	first
	all of these
	third

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.

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 closer to the fulcrum
	move the object being lifted farther away from the fulcrum

Solution

3 If input effort is 300 ft⋅lb, what output effort will be produced by a machine with a mechanical advantage of 3?

79% Answer Correctly

	1800ft⋅lb
	3600ft⋅lb
	450ft⋅lb
	900 ft⋅lb

Solution

Mechanical advantage is the ratio of output force to input force and tells us by how many times a machine multiplies input effort. So, a machine with a mechanical advantage of 3 will multiply an input effort of 300 ft⋅lb by 3 to produce an output effort of 900 ft⋅lb.

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

69% Answer Correctly

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

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.

When all forces acting on a system cancel each other out, this is called:

80% Answer Correctly

	potential energy
	equilibrium
	stasis
	rest

Solution

When a system is stable or balanced (equilibrium) all forces acting on the system cancel each other out. In the case of torque, equilibrium means that the sum of the anticlockwise moments about a center of rotation equal the sum of the clockwise moments.