ASVAB Mechanical Comprehension Practice Test 202946 Results

	Your Results	Global Average
Questions	5	5
Correct	0	3.35
Score	0%	67%

Review

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

37% Answer Correctly

	the speed of the load
	the distance traveled by the load
	the mechanical advantage of the lever
	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.

2 If input effort is 200 ft⋅lb, what output effort will be produced by a machine with a mechanical advantage of 7?

79% Answer Correctly

	1400 ft⋅lb
	2800ft⋅lb
	350ft⋅lb
	5600ft⋅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 7 will multiply an input effort of 200 ft⋅lb by 7 to produce an output effort of 1400 ft⋅lb.

3 How much resistance could a 165 lb. effort force lift using a block and tackle pulley that has 10 ropes supporting the resistance?

81% Answer Correctly

	3300 lbs.
	4950 lbs.
	1650 lbs.
	1815 lbs.

Solution

The mechanical advantage (MA) of a block and tackle pulley is equal to the number of times the effort force changes direction. An easy way to count how many times the effort force changes direction is to count the number of ropes that support the resistance which, in this problem, is 10. With a MA of 10, a 165 lbs. effort force could lift 165 lbs. x 10 = 1650 lbs. resistance.

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

80% Answer Correctly

	equilibrium
	stasis
	rest
	potential energy

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.

A wedge converts force applied to its blunt end into force __________ its inclined surface.

57% Answer Correctly

	along
	opposite to
	perpendicular to
	parallel to

Solution

The wedge is a moving inclined plane that is used to lift, hold, or break apart an object. A wedge converts force applied to its blunt end into force perpendicular to its inclined surface. In contrast to a stationary plane where force is applied to the object being moved, with a wedge the object is stationary and the force is being applied to the plane. Examples of a wedge include knives and chisels.