ASVAB Mechanical Comprehension Practice Test 647493 Results

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

Review

The principle of moments defines equilibrium in terms of:

53% Answer Correctly

	speed
	power
	energy
	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.

Depending on where you apply effort and resistance, the wheel and axle can multiply:

45% Answer Correctly

	power or distance
	force or speed
	force or distance
	speed or power

Solution

If you apply the resistance to the axle and the effort to the wheel, the wheel and axle will multiply force and if you apply the resistance to the wheel and the effort to the axle, it will multiply speed.

Which of the following surfaces would have the lowest coefficient of friction?

85% Answer Correctly

	leather
	concrete
	ice
	tile

Solution

Coefficient of friction (μ) represents how much two materials resist sliding across each other. Smooth surfaces like ice have low coefficients of friction while rough surfaces like concrete have high μ.

4 How much resistance could a 130 lb. effort force lift using a block and tackle pulley that has 10 ropes supporting the resistance?

81% Answer Correctly

	1303 lbs.
	1950 lbs.
	1300 lbs.
	2600 lbs.

Solution

The mechanical advantage (MA) of a block and tackle pulley is equal to the number of times the effort force changes direction. An easy way to count how many times the effort force changes direction is to count the number of ropes that support the resistance which, in this problem, is 10. With a MA of 10, a 130 lbs. effort force could lift 130 lbs. x 10 = 1300 lbs. resistance.

For any given surface, the coefficient of static friction is ___________ the coefficient of kinetic friction.

54% Answer Correctly

	lower than
	higher than
	equal to
	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).