ASVAB Mechanical Comprehension Practice Test 913429 Results

	Your Results	Global Average
Questions	5	5
Correct	0	3.18
Score	0%	64%

Review

Two or more pulleys used together are called:

71% Answer Correctly

	gears
	third-class lever
	block and tackle
	wheel and axle

Solution

Two or more pulleys used together constitute a block and tackle which, unlike a fixed pulley, does impart mechanical advantage as a function of the number of pulleys that make up the arrangement. So, for example, a block and tackle with three pulleys would have a mechanical advantage of three.

The force exerted on an object due to gravity is called:

69% Answer Correctly

	mass
	weight
	potential energy
	density

Solution

Mass is an intrinsic property of matter and does not vary. Weight is the force exerted on the mass of an object due to gravity and a specific case of Newton's Second Law of Motion. Replace force with weight and acceleration with acceleration due to gravity on Earth (g) and the result is the formula for weight: W = mg or, substituting for g, weight equals mass multiplied by 9.8 m/s².

Sam can do 50 ft. lb. of work in 2 minutes and 5 seconds. What would Sam have to do to increase his power output?

63% Answer Correctly

	do the work in 3 minutes
	do 25 ft. lb. of work in 2 minutes 5 seconds
	do the work in 2 minutes
	do 100 ft. lb. of work in 4 minutes 12 seconds

Solution

Power is the rate of doing work or \(\frac{W}{t}\). To increase power, increase the work being done in the same amount of time or do the same amount of work in less time.

4 How much work can a 9 hp engine do in 9 seconds?

52% Answer Correctly

	4 ft⋅lb
	44550 ft⋅lb
	2 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:
\( W = 9 hp \times 550 \frac{ft⋅lb}{s} \times 9s = 44550 ft⋅lb \)

What is work?

60% Answer Correctly

	The movement of an object by a force
	Force per unit distance
	Force per unit time
	The potential for exertion

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. By definition, work is the displacement of an object resulting from applied force.