ASVAB Mechanical Comprehension Practice Test 614757 Results

	Your Results	Global Average
Questions	5	5
Correct	0	2.84
Score	0%	57%

Review

The science that deals with motion and the forces that produce motion is called which of the following?

57% Answer Correctly

	aeronautics
	mechanics
	physics
	engineering

Solution

Mechanics deals with motion and the forces that produce motion.

When it comes to force, mass and acceleration have what kind of relationship?

65% Answer Correctly

	inverse
	linear
	logarithmic
	exponential

Solution

Newton's Second Law of Motion states that "The acceleration of an object as produced by a net force is directly proportional to the magnitude of the net force, in the same direction as the net force, and inversely proportional to the mass of the object." This Law describes the linear relationship between mass and acceleration when it comes to force and leads to the formula F = ma or force equals mass multiplied by rate of acceleration.

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

59% Answer Correctly

	only if normal force is present
	at all times
	if the coefficient of friction is greater than one
	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 If A = 10 ft., B = 3 ft., C = 5 ft., the green box weighs 50 lbs. and the blue box weighs 60 lbs., what does the orange box have to weigh for this lever to balance?

44% Answer Correctly

	192 lbs.
	256 lbs.
	0 lbs.
	64 lbs.

Solution

In order for this lever to balance, the torque acting on each side of the fulrum must be equal. So, the torque produced by A must equal the torque produced by B and C. 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 + f_Cd_C

For this problem, this equation becomes:

50 lbs. x 10 ft. = 60 lbs. x 3 ft. + f_C x 5 ft.

500 ft. lbs. = 180 ft. lbs. + f_C x 5 ft.

f_C = \( \frac{500 ft. lbs. - 180 ft. lbs.}{5 ft.} \) = \( \frac{320 ft. lbs.}{5 ft.} \) = 64 lbs.

Which class of lever is used to increase force on an object in the same direction as the force is applied?

53% Answer Correctly

	second
	first
	all of these
	third

Solution

A second-class lever is used to increase force on an object in the same direction as the force is applied. This lever requires a smaller force to lift a larger load but the force must be applied over a greater distance. The fulcrum is placed at one end of the lever and mechanical advantage increases as the object being lifted is moved closer to the fulcrum or the length of the lever is increased. An example of a second-class lever is a wheelbarrow.