ASVAB Mechanical Comprehension Practice Test 537038 Results

	Your Results	Global Average
Questions	5	5
Correct	0	3.21
Score	0%	64%

Review

1 If A = 1 ft. and the green box weighs 20 lbs. what is the torque acting on the A side of this lever?

75% Answer Correctly

	40 ft⋅lb
	20 ft⋅lb
	6 ft⋅lb
	10 ft⋅lb

Solution

For a lever, torque is weight x distance from the fulcrum which, in this case, is: 20 ft. x 1 lbs. = 20 ft⋅lb

Sam can do 50 ft. lb. of work in 2 minutes and 5 seconds. What would Sam have to do to increase his power output?

64% Answer Correctly

	do the work in 2 minutes
	do 100 ft. lb. of work in 4 minutes 12 seconds
	do the work in 3 minutes
	do 25 ft. lb. of work in 2 minutes 5 seconds

Solution

Power is the rate of doing work or \(\frac{W}{t}\). To increase power, increase the work being done in the same amount of time or do the same amount of work in less time.

What is work?

60% Answer Correctly

	The potential for exertion
	Force per unit time
	The movement of an object by a force
	Force per unit distance

Solution

Work is accomplished when force is applied to an object: W = Fd where F is force in newtons (N) and d is distance in meters (m). Thus, the more force that must be applied to move an object, the more work is done and the farther an object is moved by exerting force, the more work is done. By definition, work is the displacement of an object resulting from applied force.

What type of load doesn't create specific stress points or vary with time?

60% Answer Correctly

	concentrated load
	non-uniformly distributed load
	static uniformly distributed load
	impact 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 40 lbs. of force is applied 7 ft. from the fulcrum at the blue arrow and the green box is 3 ft. from the fulcrum, how much would the green box have to weigh to balance the lever?

62% Answer Correctly

	5 lbs.
	186.67 lbs.
	280 lbs.
	93.33 lbs.

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 R_a, our missing value, and plugging in our variables yields:

R_a = \( \frac{R_bd_b}{d_a} \) = \( \frac{40 lbs. \times 7 ft.}{3 ft.} \) = \( \frac{280 ft⋅lb}{3 ft.} \) = 93.33 lbs.