ASVAB Mechanical Comprehension Practice Test 295183 Results

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

Review

1

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

61% Answer Correctly

decrease, increase

decrease, decrease

increase, increase

increase, decrease
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

Which of the following statements about this pulley configuration is false?

48% Answer Correctly

Only multiplies the effort force

Changes the direction of and multiplies the effort force

This is a block and tackle pulley configuration

Mechanical advantage is the number of ropes that support the resistance
Solution

A block and tackle is a combination of one or more fixed pulleys and one or more movable pulleys where the fixed pulleys change the direction of the effort force and the movable pulleys multiply it. The mechanical advantage is equal to the number of times the effort force changes direction and can be increased by adding more pulley wheels to the system. An easy way to find the mechanical advantage of a block and tackle pulley system is to count the number of ropes that support the resistance.

3 What is the efficiency of a machine has work input of 250 ft⋅lb and work output of 175 ft⋅lb?
67% Answer Correctly
35%
70%
30%
140%
Solution
Due to friction, a machine will never be able to utilize 100% of its work input. A certain percentage of that input will be lost in overcoming friction within the machine. Effeciency is a measure of how much of a machine's work input can be turned into useful work output and is calculated by dividing work output by work input and multiplying the result by 100:
\( Efficiency = \frac{Work_{out}}{Work_{in}} \times 100 \) \( = \frac{175 ft⋅lb}{250 ft⋅lb} \times 100 \) \( = 70% \) %
4

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

84% Answer Correctly

none of these

first-class lever

wedge

inclined plane
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.

5

An inclined plane increases ___________ to reduce ____________.

58% Answer Correctly

distance, power

force, distance

distance, force

force, power
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.