ASVAB Mechanical Comprehension Practice Test 949752 Results

	Your Results	Global Average
Questions	5	5
Correct	0	3.18
Score	0%	64%

Review

1 If A = 3 ft. and the green box weighs 50 lbs. what is the torque acting on the A side of this lever?

74% Answer Correctly

	450 ft⋅lb
	75 ft⋅lb
	50 ft⋅lb
	150 ft⋅lb

Solution

For a lever, torque is weight x distance from the fulcrum which, in this case, is: 50 ft. x 3 lbs. = 150 ft⋅lb

2 If the handles of a wheelbarrow are 1.0 ft. from the wheel axle, how many pounds of force must you exert to lift the handles if it's carrying a 110 lbs. load concentrated at a point 1.0 ft. from the axle?

52% Answer Correctly

	75.2
	110
	-32
	0

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: F_ed_e = F_rd_r. In this problem we're looking for effort force:
\( F_e = \frac{F_r d_r}{d_e} \)
\( F_e = \frac{110 \times 1.0}{1.0} \)
\( F_e = \frac{110.0}{1.0} \)
\( F_e = 110 \)

The measure of how much of the power put into a machine is turned into movement or force is called:

56% Answer Correctly

	power
	efficiency
	mechanical advantage
	force multiplication

Solution

The efficiency of a machine describes how much of the power put into the machine is turned into movement or force. A 100% efficient machine would turn all of the input power into output movement or force. However, no machine is 100% efficient due to friction, heat, wear and other imperfections that consume input power without delivering any output.

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

69% Answer Correctly

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

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.

What type of load varies with time or affects a structure that experiences a high degree of movement?

66% Answer Correctly

	impact load
	dynamic load
	static load
	concentrated load

Solution

A concentrated load acts on a relatively small area of a structure, a static uniformly distributed load doesn't create specific stress points or vary with time, a dynamic load varies with time or affects a structure that experiences a high degree of movement, an impact load is sudden and for a relatively short duration and a non-uniformly distributed load creates different stresses at different locations on a structure.