ASVAB Mechanical Comprehension Practice Test 75783 Results

	Your Results	Global Average
Questions	5	5
Correct	0	2.88
Score	0%	58%

Review

Torque involves a perpendicular force applied to a lever arm that moves around a center of rotation. Increasing the length of the lever arm will do which of the following?

55% Answer Correctly

	increase torque
	increase applied force
	decrease applied force
	decrease torque

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).

The principle of moments defines equilibrium in terms of:

54% Answer Correctly

	power
	energy
	speed
	torque

Solution

According to the principle of moments, you can maintain equilibrium if the moments (forces) tending to clockwise rotation are equal to the moments tending to counterclockwise rotation. Another name for these moments of force is torque.

3 What is the power output of a 4 hp engine that's 75% efficient?

40% Answer Correctly

	3300 \( \frac{ft⋅lb}{s} \)
	4950 \( \frac{ft⋅lb}{s} \)
	6600 \( \frac{ft⋅lb}{s} \)
	1650 \( \frac{ft⋅lb}{s} \)

Solution

\( Efficiency = \frac{Power_{out}}{Power_{in}} \times 100 \)
Solving for power out: \( P_{o} = \frac{E \times P_{i}}{100} \)
Knowing that 1 hp = 550 \( \frac{ft⋅lb}{s} \), P_i becomes 4 hp x 550 \( \frac{ft⋅lb}{s} \) = 2200 \( \frac{ft⋅lb}{s} \)
\( P_{o} = \frac{E \times P_{i}}{100} = \frac{75 \times 2200 \frac{ft⋅lb}{s}}{100} \) \( = \frac{165000 \frac{ft⋅lb}{s}}{100} \) = 1650 \( \frac{ft⋅lb}{s} \)

Coplanar forces:

62% Answer Correctly

	act in a common plane
	act along the same line of action
	pass through a common point
	have opposite dimensions

Solution

Collinear forces act along the same line of action, concurrent forces pass through a common point and coplanar forces act in a common plane.

The force required to initally get an object moving is __________ the force required to keep it moving.

76% Answer Correctly

	higher than
	the same as
	lower than
	opposite

Solution

For any given surface, the coefficient of static friction is higher than the coefficient of kinetic friction. More force is required to initally get an object moving than is required to keep it moving. Additionally, static friction only arises in response to an attempt to move an object (overcome the normal force between it and the surface).