ASVAB Mechanical Comprehension Practice Test 249994 Results

Your Results Global Average
Questions 5 5
Correct 0 3.02
Score 0% 60%

Review

1

On Earth, acceleration due to gravity (g) is approximately __________. 

81% Answer Correctly

6.67 x 10-11 m/s2

9.8 m/s2

1 m/s

1 m/s2
Solution

Newton's Law of Univeral Gravitation defines the general formula for the attraction of gravity between two objects:  \(\vec{F_{g}} = { Gm_{1}m_{2} \over r^2}\) . In the specific case of an object falling toward Earth, the acceleration due to gravity (g) is approximately 9.8 m/s2. 

2

Assuming force applied remains constant, which of the following will result in more work being done?

53% Answer Correctly

moving the object with more speed

moving the object farther

moving the object with more acceleration

increasing the coefficient of friction
Solution

Work is accomplished when force is applied to an object: W = Fd where F is force in newtons (N) and d is distance in meters (m). Thus, the more force that must be applied to move an object, the more work is done and the farther an object is moved by exerting force, the more work is done.

3 If A = 8 ft., B = 3 ft., C = 7 ft., the green box weighs 35 lbs. and the blue box weighs 40 lbs., what does the orange box have to weigh for this lever to balance?
44% Answer Correctly
22.86 lbs.
105 lbs.
11 lbs.
7.62 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:

fAdA = fBdB + fCdC

For this problem, this equation becomes:

35 lbs. x 8 ft. = 40 lbs. x 3 ft. + fC x 7 ft.

280 ft. lbs. = 120 ft. lbs. + fC x 7 ft.

fC = \( \frac{280 ft. lbs. - 120 ft. lbs.}{7 ft.} \) = \( \frac{160 ft. lbs.}{7 ft.} \) = 22.86 lbs.

4

What is the first step to solving a problem where multiple forces are acting on an object?

61% Answer Correctly

calculate kinetic energy

calculate the total force

calculate the net force

calculate potential energy
Solution

In mechanics, multiple forces are often acting on a particular object and, taken together, produce the net force acting on that object. Like force, net force is a vector quantity in that it has magnitude and direction.

5 The radius of the axle is 3, the radius of the wheel is 8, and the blue box weighs 70 lbs. What is the effort force necessary to balance the load?
53% Answer Correctly
26.22 lbs.
3 lbs.
8 lbs.
11 lbs.
Solution

The mechanical advantage of a wheel and axle is the input radius divided by the output radius:

MA = \( \frac{r_i}{r_o} \)

In this case, the input radius (where the effort force is being applied) is 8 and the output radius (where the resistance is being applied) is 3 for a mechanical advantage of \( \frac{8}{3} \) = 2.67

MA = \( \frac{load}{effort} \) so effort = \( \frac{load}{MA} \) = \( \frac{70 lbs.}{2.67} \) = 26.22 lbs.