ASVAB Mechanical Comprehension Practice Test 781585 Results

	Your Results	Global Average
Questions	5	5
Correct	0	3.40
Score	0%	68%

Review

A fixed pulley has a mechanical advantage of:

68% Answer Correctly

	2
	0
	-1
	1

Solution

A fixed pulley is used to change the direction of a force and does not multiply the force applied. As such, it has a mechanical advantage of one. The benefit of a fixed pulley is that it can allow the force to be applied at a more convenient angle, for example, pulling downward or horizontally to lift an object instead of upward.

2 If the green arrow in this diagram represents 650 ft⋅lb of work, how far will the box move if it weighs 130 pounds?

72% Answer Correctly

	5 ft.
	65 ft.
	0 ft.
	260 ft.

Solution

The Law of Work states that the work put into a machine is equal to the work received from the machine under ideal conditions. In equation form, that's:

W_in = W_out
F_effort x d_effort = F_resistance x d_resistance

In this problem, the effort work is 650 ft⋅lb and the resistance force is 130 lbs. and we need to calculate the resistance distance:

W_in = F_resistance x d_resistance
650 ft⋅lb = 130 lbs. x d_resistance
d_resistance = \( \frac{650ft⋅lb}{130 lbs.} \) = 5 ft.

Friction between two or more solid objects that are not moving relative to each other is called:

73% Answer Correctly

	static friction
	gravitational friction
	dynamic friction
	kinetic friction

Solution

Static friction is friction between two or more solid objects that are not moving relative to each other. An example is the friction that prevents a box on a sloped surface from sliding farther down the surface.

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?

54% Answer Correctly

	increase applied force
	decrease applied force
	decrease torque
	increase 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).

Collinear forces:

72% Answer Correctly

	act along the same line of action
	pass through a common point
	act in a common plane
	are unrelated to each other

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.