ASVAB Mechanical Comprehension Practice Test 192477 Results

	Your Results	Global Average
Questions	5	5
Correct	0	3.00
Score	0%	60%

Review

1 If you lift a 28 lbs. rock 5 ft. from the ground, how much work have you done?

70% Answer Correctly

	None of these is correct
	23 ft⋅lb
	70 ft⋅lb
	140 ft⋅lb

Solution

Work is force times distance. In this case, the force is the weight of the rock so:
\( W = F \times d \)
\( W = 28 \times 5 \)
\( W = 140 \)

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

61% Answer Correctly

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

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.

Connected gears of different numbers of teeth are used together to change which of the following charasteristics of the input force?

65% Answer Correctly

	torque
	rotational direction
	force
	energy

Solution

A screw is most like which of the following other simple machines?

50% Answer Correctly

	wheel and axle
	block and tackle
	first-class lever
	inclined plane

Solution

A screw is an inclined plane wrapped in ridges (threads) around a cylinder. The distance between these ridges defines the pitch of the screw and this distance is how far the screw advances when it is turned once. The mechanical advantage of a screw is its circumference divided by the pitch.

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 farther
	moving the object with more speed
	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.