ASVAB Mechanical Comprehension Practice Test 538505 Results

	Your Results	Global Average
Questions	5	5
Correct	0	3.25
Score	0%	65%

Review

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?

64% Answer Correctly

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

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.

A block and tackle with four pulleys would have a mechanical advantage of:

79% Answer Correctly

	1
	0
	2
	4

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.

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

53% Answer Correctly

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

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.

If the handles of a wheelbarrow are 3 ft. from the wheel axle, what force must you exert to lift the handles if it's carrying a 270 lb. load concentrated at a point 0.5 ft. from the axle?

56% Answer Correctly

	0.83 lbs
	810 lbs
	45 lbs
	90 lbs

Solution

This problem describes a second-class lever and, for a second class lever, the effort force multiplied by the effort distance equals the resistance force multipied by the resistance distance: F_ed_e = F_rd_r. Plugging in the variables from this problem yields:

F_e x 3 ft. = 270 lbs x 0.5 ft
F_e = 135 ft-lb. / 3 ft
F_e= 45 lbs

The standard unit of energy is the:

73% Answer Correctly

	Watt
	Horsepower
	Joule
	Volt

Solution

The Joule (J) is the standard unit of energy and has the unit \({kg \times m^2} \over s^2\).