ASVAB Mechanical Comprehension Practice Test 526249 Results

Your Results Global Average
Questions 5 5
Correct 0 3.30
Score 0% 66%

Review

1

Which of the following is the formula for torque?

62% Answer Correctly

τ = F/r2

τ = rF

τ = r/F

τ = F/r
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).

2 If A = 9 ft. and the green box weighs 45 lbs. what is the torque acting on the A side of this lever?
75% Answer Correctly
810 ft⋅lb
405 ft⋅lb
1215 ft⋅lb
1620 ft⋅lb
Solution
For a lever, torque is weight x distance from the fulcrum which, in this case, is: 45 ft. x 9 lbs. = 405 ft⋅lb
3 If the green box weighs 75 lbs. and is 3 ft. from the fulcrum, how far from the fulcrum would a 65 lbs. force need to be applied to balance the lever?
58% Answer Correctly
3.46 ft.
1.15 ft.
0 ft.
1.73 ft.
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 db, our missing value, and plugging in our variables yields:

db = \( \frac{R_ad_a}{R_b} \) = \( \frac{75 lbs. \times 3 ft.}{65 lbs.} \) = \( \frac{225 ft⋅lb}{65 lbs.} \) = 3.46 ft.

4

Coplanar forces:

62% Answer Correctly

act in a common plane

pass through a common point

act along the same line of action

have opposite dimensions
Solution

Collinear forces act along the same line of action, concurrent forces pass through a common point and coplanar forces act in a common plane.

5

Collinear forces:

73% Answer Correctly

pass through a common point

act along the same line of action

are unrelated to each other

act in a common plane
Solution

Collinear forces act along the same line of action, concurrent forces pass through a common point and coplanar forces act in a common plane.