ASVAB Mechanical Comprehension Practice Test 461945 Results

	Your Results	Global Average
Questions	5	5
Correct	0	3.16
Score	0%	63%

Review

1 A = 5 ft., the green box weighs 15 lbs., and the blue box weighs 20 lbs. What does distance B need to be for this lever to balance?

65% Answer Correctly

	15 ft.
	7.5 ft.
	3 ft.
	3.75 ft.

Solution

In order for this lever to balance, the torque acting on side A must equal the torque acting on side B. Torque is weight x distance from the fulcrum which means that the following must be true for the lever to balance:

f_Ad_A = f_Bd_B

For this problem, the equation becomes:

15 lbs. x 5 ft. = 20 lbs. x d_B

d_B = \( \frac{15 \times 5 ft⋅lb}{20 lbs.} \) = \( \frac{75 ft⋅lb}{20 lbs.} \) = 3.75 ft.

Which of the following is not a type of bridge?

74% Answer Correctly

	block
	truss
	cable
	arch

Solution

The six basic bridge forms are beam, truss, arch, cantilever, cable, and suspension.

The measure of how much of the power put into a machine is turned into movement or force is called:

56% Answer Correctly

	mechanical advantage
	efficiency
	force multiplication
	power

Solution

The efficiency of a machine describes how much of the power put into the machine is turned into movement or force. A 100% efficient machine would turn all of the input power into output movement or force. However, no machine is 100% efficient due to friction, heat, wear and other imperfections that consume input power without delivering any output.

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

62% Answer Correctly

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

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).

A box is resting on a smooth floor. Static friction is present:

60% Answer Correctly

	at all times
	when an attempt is made to move the box
	only if normal force is present
	if the coefficient of friction is greater than one

Solution

For any given surface, the coefficient of static friction is higher than the coefficient of kinetic friction. More force is required to initally get an object moving than is required to keep it moving. Additionally, static friction only arises in response to an attempt to move an object (overcome the normal force between it and the surface).