ASVAB Mechanical Comprehension Practice Test 697067 Results

	Your Results	Global Average
Questions	5	5
Correct	0	3.35
Score	0%	67%

Review

1 If you lift a 13 lbs. rock 30 ft. from the ground, how much work have you done?

71% Answer Correctly

	0 ft⋅lb
	390 ft⋅lb
	2 ft⋅lb
	None of these is correct

Solution

Work is force times distance. In this case, the force is the weight of the rock so:
\( W = F \times d \)
\( W = 13 \times 30 \)
\( W = 390 \)

The mechanical advantage of a block and tackle is equal to which of the following?

69% Answer Correctly

	the number of loads
	the number of connecting ropes
	the number of input forces
	the number of pulleys

Solution

Two or more pulleys used together constitute a block and tackle which, unlike a fixed pulley, does impart mechanical advantage as a function of the number of pulleys that make up the arrangement. So, for example, a block and tackle with three pulleys would have a mechanical advantage of three.

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

61% Answer Correctly

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

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).

Which of the following is the formula for torque?

61% Answer Correctly

	τ = F/r
	τ = r/F
	τ = F/r²
	τ = rF

Solution

Torque measures force applied during rotation: τ = rF. Torque (τ, the Greek letter tau) = the radius of the lever arm (r) multiplied by the force (F) applied. Radius is measured from the center of rotation or fulcrum to the point at which the perpendicular force is being applied. The resulting unit for torque is newton-meter (N-m) or foot-pound (ft-lb).

Hydraulics is the transmission of force through the use of which of the following?

73% Answer Correctly

	liquids
	gear systems
	torque
	air pressure

Solution

Hydraulics is the transmission of force through the use of liquids. Liquids are especially suited for transferring force in complex machines because they compress very little and can occupy very small spaces. Hydraulic pressure is calculated by dividing force by the area over which it is applied: P = F/A where F is force in pounds, A is area in square inches, and the resulting pressure is in pounds per square inch (psi).