ASVAB Mechanical Comprehension Practice Test 882758 Results

	Your Results	Global Average
Questions	5	5
Correct	0	2.90
Score	0%	58%

Review

1 If the handles of a wheelbarrow are 1.5 ft. from the wheel axle, how many pounds of force must you exert to lift the handles if it's carrying a 260 lbs. load concentrated at a point 1.5 ft. from the axle?

52% Answer Correctly

	None of these is correct
	210.6
	-68
	260

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. In this problem we're looking for effort force:
\( F_e = \frac{F_r d_r}{d_e} \)
\( F_e = \frac{260 \times 1.5}{1.5} \)
\( F_e = \frac{390.0}{1.5} \)
\( F_e = 260 \)

Power is the rate at which:

62% Answer Correctly

	input force is transferred to output force
	friction is overcome
	potential energy is converted into kinetic energy
	work is done

Solution

Power is the rate at which work is done, P = w/t, or work per unit time. The watt (W) is the unit for power and is equal to 1 joule (or newton-meter) per second. Horsepower (hp) is another familiar unit of power used primarily for rating internal combustion engines. 1 hp equals 746 watts.

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
	increase, increase
	decrease, 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.

Potential energy is energy that has the potential to be converted into what?

81% Answer Correctly

	work
	power
	kinetic energy
	heat

Solution

Potential energy is the energy of an object by virtue of its position relative to other objects. It is energy that has the potential to be converted into kinetic energy.

What's the last gear in a gear train called?

38% Answer Correctly

	driver gear
	output gear
	driven gear
	idler gear

Solution

A gear train is two or more gears linked together. Gear trains are designed to increase or reduce the speed or torque outpout of a rotating system or change the direction of its output. The first gear in the chain is called the driver and the last gear in the chain the driven gear with the gears between them called idler gears.