ASVAB Mechanical Comprehension Practice Test 13040 Results

	Your Results	Global Average
Questions	5	5
Correct	0	3.17
Score	0%	63%

Review

Sam can do 50 ft. lb. of work in 2 minutes and 5 seconds. What would Sam have to do to increase his power output?

64% Answer Correctly

	do the work in 3 minutes
	do the work in 2 minutes
	do 100 ft. lb. of work in 4 minutes 12 seconds
	do 25 ft. lb. of work in 2 minutes 5 seconds

Solution

Power is the rate of doing work or \(\frac{W}{t}\). To increase power, increase the work being done in the same amount of time or do the same amount of work in less time.

2 If you lift a 5 lbs. rock 25 ft. from the ground, how much work have you done?

70% Answer Correctly

	50 ft⋅lb
	250 ft⋅lb
	0 ft⋅lb
	125 ft⋅lb

Solution

Work is force times distance. In this case, the force is the weight of the rock so:
\( W = F \times d \)
\( W = 5 \times 25 \)
\( W = 125 \)

Which of these is the formula for kinetic energy?

67% Answer Correctly

	\(KE = {m \over v^2 }\)
	\(KE = {1 \over 2}mv^2\)
	\(KE = mgh\)
	\(KE = {1 \over 2}mh^2\)

Solution

Kinetic energy is the energy of movement and is a function of the mass of an object and its speed: \(KE = {1 \over 2}mv^2\) where m is mass in kilograms, v is speed in meters per second, and KE is in joules. The most impactful quantity to kinetic energy is velocity as an increase in mass increases KE linearly while an increase in speed increases KE exponentially.

4 If 50 lbs. of force is applied 6 ft. from the fulcrum at the blue arrow and the green box is 5 ft. from the fulcrum, how much would the green box have to weigh to balance the lever?

62% Answer Correctly

	60 lbs.
	120 lbs.
	15 lbs.
	0 lbs.

Solution

To balance this lever the torques at the green box and the blue arrow must be equal. Torque is weight x distance from the fulcrum so the equation for equilibrium is:

R_ad_a = R_bd_b

where a represents the green box and b the blue arrow, R is resistance (weight/force) and d is the distance from the fulcrum.

Solving for R_a, our missing value, and plugging in our variables yields:

R_a = \( \frac{R_bd_b}{d_a} \) = \( \frac{50 lbs. \times 6 ft.}{5 ft.} \) = \( \frac{300 ft⋅lb}{5 ft.} \) = 60 lbs.

The science that deals with motion and the forces that produce motion is called which of the following?

57% Answer Correctly

	aeronautics
	mechanics
	physics
	engineering

Solution

Mechanics deals with motion and the forces that produce motion.