ASVAB Mechanical Comprehension Practice Test 903858 Results

Your Results Global Average
Questions 5 5
Correct 0 3.17
Score 0% 63%

Review

1 How much work can a 9 hp engine do in 5 seconds?
52% Answer Correctly
24750 ft⋅lb
18 ft⋅lb
4 ft⋅lb
36 ft⋅lb
Solution
Horsepower (hp) is a common measure of power output for complex machines. By definition, a 1 hp machine does 550 ft⋅lb of work in 1 second: 1 hp = 550 ft⋅lb/s. Substituting the variables for this problem gives us:
\( W = 9 hp \times 550 \frac{ft⋅lb}{s} \times 5s = 24750 ft⋅lb \)
2

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

66% Answer Correctly

logarithmic

linear

exponential

inverse
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.

3

Torque involves a perpendicular force applied to a lever arm that moves around a center of rotation. Increasing the length of the lever arm will do which of the following?

55% Answer Correctly

decrease applied force

increase applied force

increase torque

decrease torque
Solution

Torque measures force applied during rotation: τ = rF.  Torque (τ, the Greek letter tau) = the radius of the lever arm (r) multiplied by the force (F) applied. Radius is measured from the center of rotation or fulcrum to the point at which the perpendicular force is being applied. The resulting unit for torque is newton-meter (N-m) or foot-pound (ft-lb).

4 If the green box weighs 5 lbs. and is 5 ft. from the fulcrum, how much force would need to be applied at the blue arrow to balance the lever if the arrow's distance from the fulcrum is 8 ft.?
62% Answer Correctly
12.5 lbs.
3.13 lbs.
1.56 lbs.
9.38 lbs.
Solution

To balance this lever the torques at the green box and the blue arrow must be equal. Torque is weight x distance from the fulcrum so the equation for equilibrium is:

Rada = Rbdb

where a represents the green box and b the blue arrow, R is resistance (weight/force) and d is the distance from the fulcrum.

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

Rb = \( \frac{R_ad_a}{d_b} \) = \( \frac{5 lbs. \times 5 ft.}{8 ft.} \) = \( \frac{25 ft⋅lb}{8 ft.} \) = 3.13 lbs.

5 What's the mechanical advantage of a wedge that's 3 inches wide and 6 inches long?
83% Answer Correctly
2
1
0
3
Solution

The mechanical advantage (MA) of a wedge is its length divided by its thickness:

MA = \( \frac{l}{t} \) = \( \frac{6 in.}{3 in.} \) = 2