ASVAB Mechanical Comprehension Practice Test 39698 Results

	Your Results	Global Average
Questions	5	5
Correct	0	3.02
Score	0%	60%

Review

Depending on where you apply effort and resistance, the wheel and axle can multiply:

45% Answer Correctly

	force or distance
	speed or power
	power or distance
	force or speed

Solution

If you apply the resistance to the axle and the effort to the wheel, the wheel and axle will multiply force and if you apply the resistance to the wheel and the effort to the axle, it will multiply speed.

2 If input effort is 500 ft⋅lb, what output effort will be produced by a machine with a mechanical advantage of 6?

79% Answer Correctly

	12000ft⋅lb
	3000 ft⋅lb
	6000ft⋅lb
	750ft⋅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 6 will multiply an input effort of 500 ft⋅lb by 6 to produce an output effort of 3000 ft⋅lb.

Two gears are connected and the smaller gear drives the larger gear. The speed of rotation will __________ and the torque will __________.

61% Answer Correctly

	decrease, decrease
	increase, decrease
	decrease, increase
	increase, increase

Solution

Connected gears of different numbers of teeth are used together to change the rotational speed and torque of the input force. If the smaller gear drives the larger gear, the speed of rotation will be reduced and the torque will increase. If the larger gear drives the smaller gear, the speed of rotation will increase and the torque will be reduced.

What type of load creates different stresses at different locations on a structure?

60% Answer Correctly

	impact load
	dynamic load
	non-uniformly distributed load
	static uniformly distributed 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.

5 If the green box weighs 5 lbs. and is 1 ft. from the fulcrum, how far from the fulcrum would a 20 lbs. force need to be applied to balance the lever?

58% Answer Correctly

	0.25 ft.
	0 ft.
	0.06 ft.
	0.08 ft.

Solution

To balance this lever the torques at the green box and the blue arrow must be equal. Torque is weight x distance from the fulcrum so the equation for equilibrium is:

R_ad_a = R_bd_b

where a represents the green box and b the blue arrow, R is resistance (weight/force) and d is the distance from the fulcrum.

Solving for d_b, our missing value, and plugging in our variables yields:

d_b = \( \frac{R_ad_a}{R_b} \) = \( \frac{5 lbs. \times 1 ft.}{20 lbs.} \) = \( \frac{5 ft⋅lb}{20 lbs.} \) = 0.25 ft.