ASVAB Mechanical Comprehension Practice Test 201529 Results

	Your Results	Global Average
Questions	5	5
Correct	0	2.54
Score	0%	51%

Review

1 If the radius of the axle is 7 and the radius of the wheel is 8, what is the mechanical advantage of this wheel and axle configuration?

41% Answer Correctly

	0.88
	8
	1
	7

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 7 and the output radius (where the resistance is being applied) is 8 for a mechanical advantage of \( \frac{7}{8} \) = 0.88

A truck is using a rope to pull a car. Tension in the rope is greatest in which of the following places?

50% Answer Correctly

	tension is equal in all parts of the rope
	in the middle
	near the car
	near the truck

Solution

Tension is a force that stretches or elongates something. When a cable or rope is used to pull an object, for example, it stretches internally as it accepts the weight that it's moving. Although tension is often treated as applying equally to all parts of a material, it's greater at the places where the material is under the most stress.

Which of the following is the formula for hydraulic pressure?

58% Answer Correctly

	P = F/A²
	P = F/A
	P = FA²
	P = FA

Solution

Hydraulics is the transmission of force through the use of liquids. Liquids are especially suited for transferring force in complex machines because they compress very little and can occupy very small spaces. Hydraulic pressure is calculated by dividing force by the area over which it is applied: P = F/A where F is force in pounds, A is area in square inches, and the resulting pressure is in pounds per square inch (psi).

4 How much work can a 6 hp engine do in 5 seconds?

52% Answer Correctly

	24 ft⋅lb
	0 ft⋅lb
	12 ft⋅lb
	16500 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:
\( W = 6 hp \times 550 \frac{ft⋅lb}{s} \times 5s = 16500 ft⋅lb \)

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

53% Answer Correctly

	increasing the coefficient of friction
	moving the object farther
	moving the object with more speed
	moving the object with more acceleration

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.