ASVAB Mechanical Comprehension Practice Test 89562 Results

	Your Results	Global Average
Questions	5	5
Correct	0	3.29
Score	0%	66%

Review

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

79% Answer Correctly

	2
	4
	0
	1

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.

2 If you lift a 12 lbs. rock 20 ft. from the ground, how much work have you done?

71% Answer Correctly

	1 ft⋅lb
	-8 ft⋅lb
	240 ft⋅lb
	120 ft⋅lb

Solution

Work is force times distance. In this case, the force is the weight of the rock so:
\( W = F \times d \)
\( W = 12 \times 20 \)
\( W = 240 \)

Which of these is the formula for kinetic energy?

68% Answer Correctly

	\(KE = {1 \over 2}mv^2\)
	\(KE = {m \over v^2 }\)
	\(KE = mgh\)
	\(KE = {1 \over 2}mh^2\)

Solution

Kinetic energy is the energy of movement and is a function of the mass of an object and its speed: \(KE = {1 \over 2}mv^2\) where m is mass in kilograms, v is speed in meters per second, and KE is in joules. The most impactful quantity to kinetic energy is velocity as an increase in mass increases KE linearly while an increase in speed increases KE exponentially.

Two gears are connected and the smaller gear drives the larger gear. The speed of rotation will __________ and the torque will __________.

61% Answer Correctly

	decrease, decrease
	decrease, increase
	increase, increase
	increase, decrease

Solution

Connected gears of different numbers of teeth are used together to change the rotational speed and torque of the input force. If the smaller gear drives the larger gear, the speed of rotation will be reduced and the torque will increase. If the larger gear drives the smaller gear, the speed of rotation will increase and the torque will be reduced.

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.