ASVAB Mechanical Comprehension Practice Test 252252 Results

Your Results Global Average
Questions 5 5
Correct 0 3.07
Score 0% 61%

Review

1

Which of the following is not a type of bridge?

74% Answer Correctly

cable

truss

arch

block
Solution

The six basic bridge forms are beam, truss, arch, cantilever, cable, and suspension.

2

Friction resists movement in a direction __________ to the movement.

81% Answer Correctly

perpendicular

normal

opposite

parallel
Solution

Friction resists movement. Kinetic (also called sliding or dynamic) friction resists movement in a direction opposite to the movement. Because it opposes movement, kinetic friction will eventually bring an object to a stop. An example is a rock that's sliding across ice.

3 The green box weighs 55 lbs. and a 45 lbs. weight is placed 3 ft. from the fulcrum at the blue arrow. How far from the fulcrum would the green box need to be placed to balance the lever?
57% Answer Correctly
0 ft.
1.23 ft.
9.82 ft.
2.45 ft.
Solution

To balance this lever the torques on each side of the fulcrum must be equal. Torque is weight x distance from the fulcrum so the equation for equilibrium is:

Rada = Rbdb

where a represents the left side of the fulcrum and b the right, R is resistance (weight) and d is the distance from the fulcrum.

Solving for da, our missing value, and plugging in our variables yields:

da = \( \frac{R_bd_b}{R_a} \) = \( \frac{45 lbs. \times 3 ft.}{55 lbs.} \) = \( \frac{135 ft⋅lb}{55 lbs.} \) = 2.45 ft.

4

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

40% Answer Correctly

lower than

the same as

higher than

opposite
Solution

The formula for force of friction (Ff) is the same whether kinetic or static friction applies: Ff = μFN. To distinguish between kinetic and static friction, μk and μs are often used in place of μ.

5

Which of the following represents how much two materials resist sliding across each other?

54% Answer Correctly

static friction

kinetic friction

normal friction

coefficient of friction
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.