ASVAB Mechanical Comprehension Practice Test 152939 Results

Your Results Global Average
Questions 5 5
Correct 0 3.10
Score 0% 62%

Review

1

Two gears are connected and the larger gear drives the smaller gear. The speed of rotation will __________ and the torque will __________.

61% Answer Correctly

decrease, decrease

decrease, increase

increase, decrease

increase, increase
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.

2 If the green box weighs 70 lbs. and is 1 ft. from the fulcrum, how far from the fulcrum would a 75 lbs. force need to be applied to balance the lever?
58% Answer Correctly
0.47 ft.
1.87 ft.
0.93 ft.
3.73 ft.
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:

Rada = Rbdb

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 db, our missing value, and plugging in our variables yields:

db = \( \frac{R_ad_a}{R_b} \) = \( \frac{70 lbs. \times 1 ft.}{75 lbs.} \) = \( \frac{70 ft⋅lb}{75 lbs.} \) = 0.93 ft.

3

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

57% Answer Correctly

physics

mechanics

aeronautics

engineering
Solution

Mechanics deals with motion and the forces that produce motion.

4 If you lift a 30 lbs. rock 30 ft. from the ground, how much work have you done?
71% Answer Correctly
0 ft⋅lb
1 ft⋅lb
None of these is correct
900 ft⋅lb
Solution
Work is force times distance. In this case, the force is the weight of the rock so:
\( W = F \times d \)
\( W = 30 \times 30 \)
\( W = 900 \)
5

Connected gears of different numbers of teeth are used together to change which of the following charasteristics of the input force?

65% Answer Correctly

rotational direction

energy

torque

force
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.