ASVAB Mechanical Comprehension Practice Test 35006 Results

	Your Results	Global Average
Questions	5	5
Correct	0	3.61
Score	0%	72%

Review

The steering wheel of a car is an example of which type of simple machine?

89% Answer Correctly

	first-class lever
	fixed pulley
	wheel and axle
	block and tackle

Solution

A wheel and axle uses two different diameter wheels mounted to a connecting axle. Force is applied to the larger wheel and large movements of this wheel result in small movements in the smaller wheel. Because a larger movement distance is being translated to a smaller distance, force is increased with a mechanical advantage equal to the ratio of the diameters of the wheels. An example of a wheel and axle is the steering wheel of a car.

Which of the following is not a type of simple machine?

58% Answer Correctly

	gear
	pulley
	lever
	screw

Solution

The six types of simple machines are the lever, wheel and axle, pulley, inclined plane, wedge, and screw.

A ramp is an example of which kind of simple machine?

84% Answer Correctly

	none of these
	first-class lever
	inclined plane
	wedge

Solution

An inclined plane is a simple machine that reduces the force needed to raise an object to a certain height. Work equals force x distance and, by increasing the distance that the object travels, an inclined plane reduces the force necessary to raise it to a particular height. In this case, the mechanical advantage is to make the task easier. An example of an inclined plane is a ramp.

4 If the green arrow in this diagram represents 300 ft⋅lb of work, how far will the box move if it weighs 150 pounds?

72% Answer Correctly

	300 ft.
	0 ft.
	2 ft.
	600 ft.

Solution

The Law of Work states that the work put into a machine is equal to the work received from the machine under ideal conditions. In equation form, that's:

W_in = W_out
F_effort x d_effort = F_resistance x d_resistance

In this problem, the effort work is 300 ft⋅lb and the resistance force is 150 lbs. and we need to calculate the resistance distance:

W_in = F_resistance x d_resistance
300 ft⋅lb = 150 lbs. x d_resistance
d_resistance = \( \frac{300ft⋅lb}{150 lbs.} \) = 2 ft.

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
	90 lbs
	45 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