ASVAB Mechanical Comprehension Practice Test 973841 Results

	Your Results	Global Average
Questions	5	5
Correct	0	3.61
Score	0%	72%

Review

Which of the following is the formula for gravitational potential energy?

62% Answer Correctly

	\(PE = { 1 \over 2} mv^2\)
	\(PE = mgh\)
	\(PE = mg^2h\)
	\(PE = { 1 \over 2} mg^2\)

Solution

Gravitational potential energy is energy by virtue of gravity. The higher an object is raised above a surface the greater the distance it must fall to reach that surface and the more velocity it will build as it falls. For gravitational potential energy, PE = mgh where m is mass (kilograms), h is height (meters), and g is acceleration due to gravity which is a constant (9.8 m/s²).

2 If you lift a 13 lbs. rock 31 ft. from the ground, how much work have you done?

71% Answer Correctly

	403 ft⋅lb
	-18 ft⋅lb
	None of these is correct
	806 ft⋅lb

Solution

Work is force times distance. In this case, the force is the weight of the rock so:
\( W = F \times d \)
\( W = 13 \times 31 \)
\( W = 403 \)

3 If A = 3 ft. and the green box weighs 20 lbs. what is the torque acting on the A side of this lever?

76% Answer Correctly

	15 ft⋅lb
	6 ft⋅lb
	20 ft⋅lb
	60 ft⋅lb

Solution

For a lever, torque is weight x distance from the fulcrum which, in this case, is: 20 ft. x 3 lbs. = 60 ft⋅lb

4 What's the mechanical advantage of a wedge that's 2 inches wide and 4 inches long?

83% Answer Correctly

	3
	2.2
	9
	2

Solution

The mechanical advantage (MA) of a wedge is its length divided by its thickness:

MA = \( \frac{l}{t} \) = \( \frac{4 in.}{2 in.} \) = 2

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

70% Answer Correctly

	potential energy
	density
	mass
	weight

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.