ASVAB Mechanical Comprehension Practice Test 816233 Results

	Your Results	Global Average
Questions	5	5
Correct	0	3.18
Score	0%	64%

Review

Coplanar forces:

62% Answer Correctly

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

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.

2 A = 8 ft., the green box weighs 30 lbs., and the blue box weighs 40 lbs. What does distance B need to be for this lever to balance?

65% Answer Correctly

	18 ft.
	6 ft.
	2 ft.
	0 ft.

Solution

In order for this lever to balance, the torque acting on side A must equal the torque acting on side B. Torque is weight x distance from the fulcrum which means that the following must be true for the lever to balance:

f_Ad_A = f_Bd_B

For this problem, the equation becomes:

30 lbs. x 8 ft. = 40 lbs. x d_B

d_B = \( \frac{30 \times 8 ft⋅lb}{40 lbs.} \) = \( \frac{240 ft⋅lb}{40 lbs.} \) = 6 ft.

A box is resting on a smooth floor. Static friction is present:

59% Answer Correctly

	only if normal force is present
	if the coefficient of friction is greater than one
	at all times
	when an attempt is made to move the box

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).

4 70 lbs. of effort is used by a machine to lift a 560 lbs. box. What is the mechanical advantage of the machine?

84% Answer Correctly

	24
	8
	8.8
	17

Solution

Mechanical advantage is resistance force divided by effort force:

MA = \( \frac{F_r}{F_e} \) = \( \frac{560 lbs.}{70 lbs.} \) = 8

A truck is using a rope to pull a car. Tension in the rope is greatest in which of the following places?

50% Answer Correctly

	tension is equal in all parts of the rope
	near the truck
	in the middle
	near the car

Solution

Tension is a force that stretches or elongates something. When a cable or rope is used to pull an object, for example, it stretches internally as it accepts the weight that it's moving. Although tension is often treated as applying equally to all parts of a material, it's greater at the places where the material is under the most stress.