ASVAB Mechanical Comprehension Practice Test 502657 Results

	Your Results	Global Average
Questions	5	5
Correct	0	3.41
Score	0%	68%

Review

1 If input effort is 300 ft⋅lb, what output effort will be produced by a machine with a mechanical advantage of 6?

79% Answer Correctly

	3600ft⋅lb
	7200ft⋅lb
	900ft⋅lb
	1800 ft⋅lb

Solution

Mechanical advantage is the ratio of output force to input force and tells us by how many times a machine multiplies input effort. So, a machine with a mechanical advantage of 6 will multiply an input effort of 300 ft⋅lb by 6 to produce an output effort of 1800 ft⋅lb.

What defines the mechanical advantage of a first class lever?

65% Answer Correctly

	position of the fulcrum
	output force
	input force
	output distance

Solution

A first-class lever is used to increase force or distance while changing the direction of the force. The lever pivots on a fulcrum and, when a force is applied to the lever at one side of the fulcrum, the other end moves in the opposite direction. The position of the fulcrum also defines the mechanical advantage of the lever. If the fulcrum is closer to the force being applied, the load can be moved a greater distance at the expense of requiring a greater input force. If the fulcrum is closer to the load, less force is required but the force must be applied over a longer distance. An example of a first-class lever is a seesaw / teeter-totter.

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

57% Answer Correctly

	driver gear
	input 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.

4 What is the mechanical advantage of this inclined plane if the length of the ramp is 21 ft. and the height of the green box is 7 ft.?

82% Answer Correctly

	9
	2.7
	3
	5

Solution

The mechanical advantage (MA) of an inclined plane is the effort distance divided by the resistance distance. In this case, the effort distance is the length of the ramp and the resistance distance is the height of the green box:

MA = \( \frac{d_e}{d_r} \) = \( \frac{21 ft.}{7 ft.} \) = 3

Which of the following is the formula for gravitational potential energy?

61% Answer Correctly

	\(PE = mg^2h\)
	\(PE = mgh\)
	\(PE = { 1 \over 2} mg^2\)
	\(PE = { 1 \over 2} mv^2\)

Solution

Gravitational potential energy is energy by virtue of gravity. The higher an object is raised above a surface the greater the distance it must fall to reach that surface and the more velocity it will build as it falls. For gravitational potential energy, PE = mgh where m is mass (kilograms), h is height (meters), and g is acceleration due to gravity which is a constant (9.8 m/s²).