ASVAB Mechanical Comprehension Practice Test 796367 Results

	Your Results	Global Average
Questions	5	5
Correct	0	2.72
Score	0%	54%

Review

Which of the following statements about drag is false?

58% Answer Correctly

	the amount of drag depends on the shape of an object
	slower objects experience more drag than faster objects
	drag occurs during movement through a fluid
	the amount of drag depends on the speed of an object

Solution

Drag is friction that opposes movement through a fluid like liquid or air. The amount of drag depends on the shape and speed of the object with slower objects experiencing less drag than faster objects and more aerodynamic objects experiencing less drag than those with a large leading surface area.

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

59% Answer Correctly

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

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).

3 If A = 11 ft., B = 2 ft., C = 7 ft., the green box weighs 40 lbs. and the blue box weighs 60 lbs., what does the orange box have to weigh for this lever to balance?

43% Answer Correctly

	440 lbs.
	91.43 lbs.
	45.71 lbs.
	22.86 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:

40 lbs. x 11 ft. = 60 lbs. x 2 ft. + f_C x 7 ft.

440 ft. lbs. = 120 ft. lbs. + f_C x 7 ft.

f_C = \( \frac{440 ft. lbs. - 120 ft. lbs.}{7 ft.} \) = \( \frac{320 ft. lbs.}{7 ft.} \) = 45.71 lbs.

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

66% Answer Correctly

	exponential
	inverse
	linear
	logarithmic

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.

Force of friction due to kinetic friction is __________ the force of friction due to static friction.

40% Answer Correctly

	higher than
	opposite
	the same as
	lower than

Solution

The formula for force of friction (F_f) is the same whether kinetic or static friction applies: F_{f =}μF_N. To distinguish between kinetic and static friction, μ_k and μ_s are often used in place of μ.