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Mechanical Comprehension Overview for ASVAB Power Practice Problems (page 2)

By LearningExpress Editors

LearningExpress, LLC

Updated on Aug 24, 2011

These mechanical comprehension practice questions are based on the actual ASVAB. Take this quiz to see how you would do if you took the exam today and to determine your strengths and weaknesses as you plan your study schedule.

Time: 19 minutes

Part 8: Mechanical Comprehension

In the diagram, Kenneth wants to balance two blocks on either side of a lever. One block weighs 27 pounds and the other weighs 24 pounds. If the 27-pound block is 4 feet to the left of the pivot point, how far to the right of the pivot point should the 24-pound block be placed?
1. 4.5 feet
2. 7 feet
3. 4 feet
4. 8.5 feet

Part 8: Mechanical Comprehension

If the rope on the end of this pulley system is pulled with 160 pounds of force, what is the maximum weight that can be lifted?
1. 640 pounds
2. 480 pounds
3. 320 pounds
4. 80 pounds

Part 8: Mechanical Comprehension

A beaker is filled with mercury and water. Mercury is a liquid with a density of 8 g/cm³ and water has a density of 1 g/cm³. If a penny with a density of 5 g/cm³ is dropped into the beaker, where will it settle?
1. at the bottom of the beaker
2. in the middle of the mercury layer
3. in between the mercury and water layers
4. on top of the water layer

Part 8: Mechanical Comprehension

A 240-pound block is being pulled up an incline by a pulley. The incline is 20 feet long and rises 5 feet. Neglecting friction, how much force is necessary to move the block up the incline?
1. 60 pounds
2. 100 pounds
3. 260 pounds
4. 240 pounds
A jack is able to lift a 3,000-pound car using only 50 pounds of force. What is the mechanical advantage of the jack?
1. 4
2. 60
3. 600
4. 2,950
The tires of a car are filled in a garage to a pressure of 35 pounds per square inch. Driving the car to a hot desert will have what effect on the tires?
1. Their pressure will increase.
2. Their pressure will decrease.
3. Their weight will increase.
4. Their weight will decrease.

Part 8: Mechanical Comprehension

A crane raises its arm using a powerful cable attached to the main body. Which cable position offers the greatest mechanical advantage?
1. A
2. B
3. C
4. They all offer the same advantage.

Part 8: Mechanical Comprehension

Two scales are connected by a plank weighing 2 pounds. A 12-pound block is placed directly in between the two scales. How many pounds will Scale 1 read?
1. 7 pounds
2. 10 pounds
3. 12 pounds
4. 14 pounds

Part 8: Mechanical Comprehension

A force of 9 pounds stretches a spring 3 inches. How far will the spring move under 12 pounds of force?
1. 3 inches
2. 4 inches
3. 6 inches
4. 36 inches
A solid object will float on water when
1. it is less dense than water.
2. it is more dense than water.
3. it has a large surface area.
4. it has a small surface area.
A nut travels 1.25 inches after 15 turns of the screw. How many threads per inch does the screw have?
1. 10
2. 12
3. 15
4. 20

Part 8: Mechanical Comprehension

Using the pulley system shown above, how much force is required to lift a 200-pound load?
1. 50 pounds
2. 100 pounds
3. 200 pounds
4. 400 pounds
Which material expands most when heated?
1. wood
2. steel
3. glass
4. rubber

Part 8: Mechanical Comprehension

Gear 1 has 12 teeth and gear 2 has 9. If the gear 1 turns at 30 rpm, how fast will gear 2 turn?
1. 20 rpm
2. 30 rpm
3. 40 rpm
4. 60 rpm

Part 8: Mechanical Comprehension

A 300-pound barrel is being supported on an incline.The incline is 18 feet long and rises 6 feet. How much force is necessary to prevent the barrel from rolling down?
1. 50 pounds
2. 100 pounds
3. 150 pounds
4. 300 pounds
A single-speed bicycle has a front chain ring with 55 teeth. The back gear has 11 teeth. If the bicycle is pedaled for 80 rpm, how many complete revolutions will the rear wheel make in 30 seconds?
1. 40 revolutions
2. 80 revolutions
3. 200 revolutions
4. 400 revolutions
400 revolutions
1. Helium is less dense than air.
2. Helium is a noble gas.
3. Helium is hotter than air.
4. Helium is colder than air.

Part 8: Mechanical Comprehension

The pulley system shown in the figure offers what advantage?
1. a two-fold mechanical advantage
2. a three-fold mechanical advantage
3. a change in the direction of force
4. no advantage

Part 8: Mechanical Comprehension

If gear 4 turns clockwise, which other gear(s) will also turn counterclockwise?
1. 1 only
2. 2 only
3. 3 only
4. 1 and 3

Part 8: Mechanical Comprehension

Two cylindrical pipes are used to drain a tank. Pipe A has a diameter of 2 inches and pipe B has a diameter of 6 inches. If there is equal water pressure inside the tank, how much more water will flow out of pipe B than pipe A?
1. The same amount will flow out of both pipes.
2. Three times more will flow out of pipe B.
3. Six times more will flow out of pipe B.
4. Nine times more will flow out of pipe B.
Steve goes on a run at 8 mph and travels 14 miles. How long did Steve run?
1. 1 hour 15 minutes
2. 1 hour 30 minutes
3. 1 hour 45 minutes
4. 2 hours

Part 8: Mechanical Comprehension

A 600-pound block is being pulled up a 15-foot incline. Neglecting friction, if 200 pounds of force is necessary to move the block up the incline, how tall is the incline?
1. 4 feet
2. 10 feet
3. 5 feet
4. 15 feet

Part 8: Mechanical Comprehension

In the diagram, Paul wants to lift a 90-pound block using a lever. If the block is 20 feet from the pivot point and Paul is 15 feet from the pivot point, how much force must he apply to lift the block?
1. 120 pounds
2. 450 pounds
3. 20 pounds
4. 90 pounds
A helium balloon is released from the ground and quickly rises 2,000 feet. What will happen to the balloon?
1. The balloon will become heavier.
2. The balloon will become lighter.
3. The size of the balloon will increase.
4. The size of the balloon will decrease.

Part 8: Mechanical Comprehension

Pulley A has 1.5 times the circumference of pulley B. If pulley A rotates counterclockwise at 30 revolutions per minute (rpm), how fast and in what direction will pulley B rotate?
1. 30 rpm clockwise
2. 30 rpm counterclockwise
3. 45 rpm clockwise
4. 45 rpm counterclockwise

Answers

a. w₁ × d₁ = w₂ × d₂. 27 pounds × 4 feet = 24 pounds × d₂. Solving for d₂ gives 4.5 feet.
b. A pulley system of this type has a mechanical advantage of 3. If 160 pounds of force is applied, a maximum weight of 160 pounds × 3 = 480 pounds can be lifted.
c. An object will float on top of a liquid if its density is less than the liquid it is in and sink if its density is greater. In this case, the penny is less dense than mercury and denser than water, so it will float on top of the mercury and sink in water, meaning it will settle directly in between the two layers.
a. The mechanical advantage (MA) of a ramp is determined by the length of the ramp, l, divided by the height gained, h. In this case, MA = = 20 feet ÷ 5 feet = 4. The force required to pull a 240-pound block up a ramp is 240 pounds ÷ 4 = 60 pounds.
b. Mechanical advantage = output force ÷ input force. Here, 50 pounds of force is input into a jack to lift a 3,000-pound car. The mechanical advantage is 3,000 ÷ 50 = 60.
a. Heating leads to an increase in pressure of a contained gas. Since no air is added or removed from the tires, their overall weight remains constant.
b. The arm acts as a lever with the pivot point being where it intersects the crane body. By attaching the cable as far along the arm as possible, the greatest mechanical advantage is achieved.
a. The total weight of the block and the plank is 14 pounds. The weight is distributed evenly between the two scales, meaning that Scale 1 will read 7 pounds.
b. The force constant of the spring is 9 pounds ÷ 3 inches = 3 pounds per inch. Using the equation, F = kx, we have 12 pounds = 3 pounds per inch × x. Solving for x gives 4 inches.
a. An object's density determines whether it will float or sink. To float, it must have a lower density than water. Surface area will not affect whether an object ultimately floats or sinks.
b. If 15 turns move the nut 1.25 inches, there are 15 turns ÷ 1.25 inches = 12 threads per inch.
b. The mechanical advantage of this pulley system is 2. The force required to lift the 200-pound load is 200 pounds ÷ 2 = 100 pounds.
b. Metals such as steel tend to expand considerably when heated. The other materials may expand somewhat when heated, but to a lesser extent.
c. Each revolution of gear 1 will turn gear 2 12 teeth ÷ 9 teeth = times. At 30 revolutions per minute, gear 2 will turn at 30 rpm × = 40 rpm.
b. The mechanical advantage (MA) of a ramp is determined by the length of the ramp, l, divided by the height gained, h. In this case, MA = = 18 feet ÷ 6 feet = 3. Since the barrel weighs 300 pounds, a force of 300 ÷ 3 = 100 pounds is required to keep the barrel in place.
c. Each turn of the pedals will move the rear wheel 55 ÷ 11 = 5 revolutions. If the bike is pedaled at 80 rpm, the rear wheel will rotate at 80 rpm × 5 revolutions = 400 rpm. Since 30 seconds is half of one minute, the rear wheel will complete 400 rpm ÷ 2 = 200 revolutions
a. Helium is less dense than air. Objects will float when they are less dense than air. Helium will float regardless of its temperature.
c. While no mechanical advantage is gained, a pulley system such as this one allows one to raise an object while pulling downward, rather than having to climb above the object to pull it.
d. If gear 4 turns clockwise, the neighboring gears 1 and 3 will turn counterclockwise.
d. The amount of water that flows out through the pipes is proportional to the size of the pipe opening. Since the area of the opening is proportional to the square of the diameter, the ratio of the amount of water that flows out of A and B is 6² ÷ 2² = 9.
c. 14 miles ÷ 8 mph = 1.75 hours = 1 hour 45 minutes.
c. If the 600-pound block can be lifted with 200 pounds of force, the ramp has a mechanical advantage (MA) of 3. The MA of a ramp is determined by the length of the ramp, l, divided by the height gained, h. In this case, . Solving for h tells us the ramp is 5 feet high.
a. w₁ × d₁ = w₂ × d₂. Paul is 15 feet away from the pivot point and the block is 20 feet away. 90 × 20 feet = 15 feet × w₂. Solving for w₂ gives 120 pounds.
c. As the balloon rises, the air pressure surrounding it will decrease and the internal pressure from the helium will press outward on the walls of the balloon, increasing it in size. Since the balloon is a closed system, its weight will be unaffected.
d. Since pulley A is 1.5 times greater in circumference than pulley B, each revolution of A will lead to 1.5 revolutions of B. The belt of the pulley will cause pulley B to move in the same direction (counterclockwise) as pulley A.

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