ASVAB Mechanical Comprehension Practice Test 77579 Results

	Your Results	Global Average
Questions	5	5
Correct	0	3.32
Score	0%	66%

Review

The force exerted on an object due to gravity is called:

70% Answer Correctly

	weight
	mass
	density
	potential energy

Solution

Mass is an intrinsic property of matter and does not vary. Weight is the force exerted on the mass of an object due to gravity and a specific case of Newton's Second Law of Motion. Replace force with weight and acceleration with acceleration due to gravity on Earth (g) and the result is the formula for weight: W = mg or, substituting for g, weight equals mass multiplied by 9.8 m/s².

2 If you lift a 31 lbs. rock 44 ft. from the ground, how much work have you done?

71% Answer Correctly

	1 ft⋅lb
	None of these is correct
	1364 ft⋅lb
	-13 ft⋅lb

Solution

Work is force times distance. In this case, the force is the weight of the rock so:
\( W = F \times d \)
\( W = 31 \times 44 \)
\( W = 1364 \)

What is work?

60% Answer Correctly

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

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.

4 If A = 3 ft. and the green box weighs 45 lbs. what is the torque acting on the A side of this lever?

74% Answer Correctly

	0 ft⋅lb
	135 ft⋅lb
	45 ft⋅lb
	540 ft⋅lb

Solution

For a lever, torque is weight x distance from the fulcrum which, in this case, is: 45 ft. x 3 lbs. = 135 ft⋅lb

Which of the following will increase the mechanical advantage of a second-class lever?

55% Answer Correctly

	move the object being lifted closer to the fulcrum
	move the fulcrum between the force and the object being lifted
	decrease the length of the lever
	move the object being lifted farther away from the fulcrum

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.