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ASVAB: Mechanical Comprehension
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The wheel of a car has a diameter of 16 inches and moves a smaller wheel of 4 inches. What is the mechanical advantage gained by the system?
a.)1:4
b.)4:1
c.)1:2
d.)2:1
b.)4:1
A lever
a.)Reduces resistance
b.)Multiplies force and changes direction
c.)Transmits power from one object to another
d.)Cannot move in the reverse direction
b.)Multiplies force and changes direction
Tension can best be called
a.)A weight
b.)A force
c.)A movement
d.)A direction
b.)A force
Which of the following wedges generates the greatest amount of force.
a.)11" long and 4" high
b.)9" long and 4" high
c.)7" long and 4" high
d.)5" long and 4" high
a.)11" long and 4" high
You're trying to replace a flat. How much torque are you applying to a wheel nut if you're applying 40 pounds with a wrench measuring 9"?
a.)4 ft-lb
b.)30 ft-lb
c.)53 ft-lb
d.)360 ft-lb
*Torque is calculated by multiplying force (in pounds) and length (in feet). Thus, 40 pounds multiplied by .75 feet gives us 30 ft-lb of torque.
1 ft=12 in
Divide 9 in by 12 ft=.75ft
b.)30 ft-lb
Which of the following situations requires overcoming the least amount of kinetic friction?
a.)Pushing an empty refrigerator box down a path
b.)Pushing a refrigerator in its box down a path
c.)Pushing an empty refrigerator box down an icy path
d.)Pushing a refrigerator in its box down an icy path
c.)Pushing an empty refrigerator box down an icy path
What measures how much force is applied to an object in order to rotate it?
a.)Torque
b.)Friction
c.)Pressure
d.)Vector
a.)Torque
Which of the following is NOT a unit of power?
a.)Watt
b.)Horsepower
c.)Volt-ampere
d.)Newton
d.)Newton
What is the potential energy of a 4 lb. book held 50 feet in the air?
a.)1,960 J
b.)268 J
c.)200 J
d.)27 J
*Potential energy is calculated by multiplying mass (in kilograms), acceleration due to gravity, and height (in meters). Thus, the potential energy of the book is 268.128 J: 1.8 kilograms multiplied by 15.2 meters multiplied by 9.8 m/s2.
b.)268 J
When a machine compounds the force you use, it gives you a(n)
a.)Mechanical advantage
b.)Output advantage
c.)Mechanical leverage
d.)Output leverage
a.)Mechanical advantage
Which of the following is an example of potential energy?
a.)Rain falling
b.)A bowling ball rolling
c.)A slinky at the top of stairs
d.)A person walking down a hill
c.)A slinky at the top of stairs
*Potential energy is energy that can be converted to movement, like a diver ABOUT to jump. Potential energy is dependent on an object's position. For example, a diver at the top of a tall cliff has considerable potential energy. Potential energy is measured in joules (J).
A 180 pound person dives off of a 30 foot cliff. What is their velocity as they enter the water?
a.)588 m/s
b.)178 m/s
c.)24 m/s
d.)13 m/s
d.)13 m/s
x = (vi)
t + (1/2)
a
t^2
30 = (0)
t + (1/2)
(32)*t^2
30 = 16*t^2
30/16 = t^2
t^2 = 1.875
t = sqrt(1.875)
t = 1.369306
vf = vi + a*t
vf = 0 + 32*1.369306
vf = 43.817792 feet per second
that converts to 13.3556630016 m/s so the answer is choice D
A perfectly efficient machine
a.)Uses the least amount of horsepower
b.)Provides the biggest mechanical advantage
c.)Converts all the power applied to it into outputted force
d.)Provides the simplest route to accomplish the task
c.)Converts all the power applied to it into outputted force
*A machine that is 100% efficient converts all of the power applied to it into output force. This is highly unlikely due to wear and tear, friction, and general imperfections.
What is the point at which the lever pivots?
a.)The force point
b.)The shaft
c.)The fulcrum
d.)The axle
c.)The fulcrum
*the point on which a lever rests or is supported and on which it pivots.
What is energy stored in chemicals or released in a chemical reaction?
a.)electrical
b.)potential
c.)chemical
d.)kinect
c.)chemical
A machine made up of two or more simple machine working together. What kind of machine is this?
a.)equilibrium
b.)compound
c.)mechanical
d.)fulcrum
b.)compound
A force that pushes materials together.
a.)effort
b.)compression
c.)resistance
d.)compound
b.)compression
In a lever, the point where you apply force.
a.)flexibility
b.)effort
c.)friction
d.)kinetic
b.)effort
In a lever, the distance from the force to the fulcrum.
a.)effort arm
b.)load arm
c.)tension
d.)potential
a.)effort arm
Energy in moving electrons
a.)potential energy
b.)electrical energy
c.)resistance
d.)effort force
b.)electrical energy
The ability of a material to bend without breaking.
a.)effort force
b.)flexibility
c.)potential
d.)resistance
b.)flexibility
The force that resists the relative motion of two surfaces in contact.
a.)effort force
b.)friction
c.)gravity
d.)load
b.)friction
An attractive force between objects
a.)effort force
b.)resistance arm
c.)power
d.)gravity
d.)gravity
Simple machines are useful in that they
a.)Simplify tasks
b.)Create a mechanical shortcut
c.)Are easy to design and build
d.)Reduce the effort needed to accomplish a task
d.)Reduce the effort needed to accomplish a task
Work occurs when
a.)Force is applied
b.)Force is applied in a certain direction
c.)Force is unable to overcome resistance
d.)Force is used to move something over a distance
d.)Force is used to move something over a distance
*Work occurs when force is used to move something, overcoming resistance, over a certain distance. Work results in movement, otherwise, it is just force. Work is calculated by multiplying force by distance. The formula is W=Fd. Work is measured in joules, force is measured in newtons, and distance is measured in meters.
15 J of work were expended moving an 18 kg block. At what velocity did the block move?
a.)1.3 m/s
b.)1.1 m/s
c.).9 m/s
d.).7 m/s
a.)1.3 m/s
*To solve for velocity, you should use the formula W = KE, where Work = W, and Kinetic Energy = KE. This is because any work that is done to accelerate an object is converted to the kinetic energy of that object (the work-energy theorem). So, W = (1/2) mv2. Plugging in the block's weight (18 kg) and the work done (15 J) will give you a velocity of 1.3 m/s.
Energy is
a.)The power of motion
b.)The application of force
c.)The capacity to do work
d.)The opposition of weight
c.)The capacity to do work
*Energy is the capacity to do work: to change something.
The measure of the quantity of matter in an object is its
a.)Mass
b.)Force
c.)Weight
d.)Density
a.)Mass
A farmer is attempting to pull a log with a line of rope attached to a tractor. Where should she watch for breakage on the rope?
a.)Nearest to the log
b.)Nearest to the tractor
c.)In the middle of the length
d.)No specific point on the length
b.)Nearest to the tractor
*The tension on the rope nearest to the tractor is the greatest. This is because tension is greatest where the force is being applied.
Power is the
a.)Amount of force
b.)Rate of work
c.)Energy of an object
d.)Difference in resistance
b.)Rate of work
What is the advantage of a single pulley?
a.)It allows you to lift something with less force
b.)It changes the direction of the effort
c.)It diminishes the effects of gravity
d.)It decreases the chances of injury
b.) It changes the direction of the effort
In terms of force, what makes hydraulic jacks so useful?
a.)The liquid is not very dense
b.)The liquid decreases the effects of gravity
c.)The liquid does not compress very much
d.)The jack spread out force over a large surface area
c.)The liquid does not compress very much
*Hydraulic jacks are useful because the liquids used to transmit force do not compress, even under high pressure. Instead, that force is transmitted to another location.
Jeremy chucks a baseball as far as he can. His arm is operating as a
a.)First-class lever
b.)Second-class lever
c.)Third-class lever
d.)Fourth-class lever
c.)Third-class lever
What is the mechanical advantage of a teeter-totter built so that each seat is 2 meters from the fulcrum?
a.)2:2
b.)4:2
c.)2:4
d.)1:2
a.)2:2
*The mechanical advantage is the ratio of the distance between the fulcrum and the point at which force is applied, and the distance between the fulcrum and the object being acted upon.
Weight is the
a.)Amount of "stuff" in an object
b.)Density of matter in an object
c.)Gravity generated by an object
d.)Force exerted on a object due to gravity
d.)Force exerted on a object due to gravity
*Mass is the amount of matter in an object; weight is the force exerted on an object due to gravity.
If a large gear drives a smaller gear, which of the following will not occur?
a.)An increase in rotational speed
b.)A decrease in torque
c.)A change in rotational direction
d.)A change in gear ratio
d.)A change in gear ratio
*The ratio of the gears (a comparison of the number of teeth on the gears) will remain the same.
"For every action there is an equal and opposite reaction" best summarizes which of Newton's Laws of Motion?
a.)Newton's First Law
b.)Newton's Second Law
c.)Newton's Third Law
d.)None of the above
c.)Newton's Third Law
*Newton's third law explains that for every action there is an equal and opposite reaction.
How is a wedge different from an inclined plane?
a.)The angles of a wedge are generally smaller
b.)A wedge provides more mechanical advantage
c.)A wedge compounds force
d.)A wedge is used in motion
d.)A wedge is used in motion
*A wedge, unlike a slide, is useful in motion. For example, a knife slicing through a carrot.
What's the formula of force?
a.)P=f/a
b.)F=m*a
c.)W=f*d
d.)P=w/t
b.)F=m*a
*force equals mass times accelatration
What's the formula of pressure?
a.)P=f/a
b.)F=m*a
c.)W=f*d
d.)P=w/t
a.)P=f/a
*pressure equals force divided by area
The property of attracting iron or steel
a.)friction
b.)magnetism
c.)mass
d.)tension
b.)magnetism
What's the formula of work?
a.)P=f/a
b.)F=m*a
c.)W=f*d
d.)P=w/t
c.)W=f*d
What's the formula of mechanical advantage?
a.)P=f/a
b.)F=m*a
c.)W=f*d
d.)MA=R/E=OF/IF
d.)MA=R/E=OF/IF
*mechanical advantage equal resistance divided by effort equal output force divided by input force
What's the formula of a lever reduces the amount of effort?
a.) LEA/LRA=RF/EF
b.)F=m*a
c.)W=f*d
d.)MA=R/E=OF/IF
a.) LEA/LRA=RF/EF
*length of effort arm divided by length of resistance arm equals resistance force divided by effort force
What's the formula of the mechanical advantage of using a lever?
a.) LEA/LRA=RF/EF
b.)MA=EA/RA
c.)W=f*d
d.)MA=R/E=OF/IF
b.)MA=EA/RA
*mechanical advantage equals effort arm divided by resistance arm
What's the formula of the mechanical advantage of using a lever?
a.) LEA/LRA=RF/EF
b.)MA=EA/RA
c.)LR/HR=WOM/FMO
d.)MA=R/E=OF/IF
c.)LR/HR=WOM/FMO
*length of ramp divided by height of ramp equal weight of object being moved divided force required to moved object
Which of the following controls an automatic sump pump?
a.)mechanical switch
b.)manual switch
c.)pneumatic switch
d.)float
d.)float
*a sump pump is used to drain water
If all the following objects are the same temperature, which one will feel coldest on a cool day?
a.) wooden spoon
b.) plastic spoon
c.) metal spoon
d.) fiberglass spoon
c.) metal spoon
A 3-inch-diameter flanged pipe with six holes is being fitted to a base with six holes. What's the maximum number of degrees the pipe must be rotated in order to line up the holes?
a.)120 degrees
b.)180 degrees
c.)60 degrees
d.)360 degrees
c.)60 degrees
*360/6=60
The moisture that forms on the inside of a window on a cold day is called?
a.)condensation
b.)distillation
c.)evaporation
d.)tarnation
a.)condensation
If a 200-pound barrel must be lifted 4 feet to the bed of a box truck, an inclined plane will reduce the amount of effort required to move the barrel by half if the incline plane is
a.)2 ft long
b.)6 ft long
c.)8 ft long
d.)9 ft long
c.)8 ft long
*x/4=200/100
x/4
4=2
4=8
While throwing a football, Dan exerts a forward force of 50 newtons on the ball and pushes it forward a distance of 1.2 meters. How much work does he do on the football?
a.)45j
b.)60j
c.)50j
d.)50.5j
b.)60j
Work=Force
Distance
=50*1.2
=60 joules
A block and tackle is used to lift a truck engine with a weight of nearly 7,406 newtons. The input force required to lift this weight using the block and tackle is 308.6 newtons. What is the mechanical advantage of block and tackle?
a.)23.99
b.)15
c.)25
d.)24.75
a.)23.99
*MA=output force/input force
=7,406/308.6= 23.99
Which of the tanks will overfill if the pipe connecting to tank A is 7 gallons/minute, the pipe connecting tank A and B are 8 gallons/minute, the pipe connecting tank B and C are 9 gallons/minute and finally the pipe connecting pipe C that is 3 gallons/minute?
a.)tank A
b.)tanks A and B
c.)tank C
d.)tanks B and C
c.) tank C
Two people are carrying a 100-pound crate on a 2-x-8-x-12 foot board. To distribute the load evenly between the two people, the crate should be placed.
a.) 2 feet from the end of the board
b.) in the middle of the board
c.)3 feet from the end of board
d.) the load can't be evenly distributed
b.) in the middle of the board
Wheel A has a diameter of 9 ft. Wheel B has a diameter of 12 ft. If both wheels revolve at the same rate, Wheel B will cover a linear distance of 24 ft.
a.)at the same speed as Wheel A
b.)more slowly than Wheel A
c.)in half the time of Wheel A
d.)more quickly than Wheel A
d.)more quickly than Wheel A
The shock absorber on a car is a very large spring. If Abra's car hits a pothole with 600 pounds of force and the shock absorber compresses 3 inches, what is its spring constant in pounds per inch?
a.)200
b.)600
c.)20
d.)1,800
d.)1,800
600
3=1,800
A 600-pound weight is placed on a 10-pound board that has been evenly balanced between two scales. How much does the left measure if the weight is 2/3 closer the left than to the right?
a.)400
b.)300
c.)405
d.)410
c.)405
600
2/3=400
2/3= 1/2= .05
400+5=405
Daisy' single-speed bicycle has a front gear with 48 teeth and a rear gear with 12 teeth. If Daisy pedaled at 80 revolutions per minute(rpm), how fast her wheel rotate?
a.)280rpm
b.)320rpm
c.)70rpm
d.)128rpm
b.)320rpm
*48/12= 4
80*4=320
Not including friction, a stationary single pulley gives a mechanical advantage of
a.)2
b.)4
c.)3
d.)1
d.)1
Four gears are connected in a series. If Gear #1 is turing clockwise, Gear #4 will turn
a.)clockwise
b.)counterclockwise
c.)more quickly than Gear #1
d.)more slowly than Gear #1
b.)counterclockwise
*gears connected in series turn in opposite directions of each other. Gear 1 and 3 turn clockwise(turn right); while Gears 2 and 4 turn counterclockwise(turn left or opposite)
James applies force at one end of a hydraulic jack. The area at the other end of the jack is five times the area where James is applying the force. How much larger is the exerted force than what James is applying?
a.)twice as large
b.)half as large
c.)one-fifth as large
d.)five times as large
d.)five times as large
*(P1=P2)/ (P=F/A)
P1=P2
F1/A1=F2/A2
F1/A1=5F1/5A1
Mr.Roth's children-Jake,Paul, and Jill-weigh 80,60 and 50 pounds, respectively. They all sit on the same side of a seesaw together. Jake sits 3 feet from the fulcrum, Paul sits 5 feet from the fulcrum, and Jill sits 6 feet from the fulcrum. How far from the fulcrum must Mr. Roth sit on the other side to balance the seesaw if he weighs 200 pounds?
a.)4.2ft
b.)5.5ft
c.)5ft
d.)4ft
a.)4.2ft
200
x=(80
3)+(60
5)+(50*6)
200x=240+300+300
200x=840
x=4.2
A rope is pulling a 320-pound box up an incline that's 16 feet long. If 80 pound of force is used to move the box up the incline, how tall is the incline?
a.)6 feet
b.)10 feet
c.)4 feet
d.)8 feet
c.)4 feet
*MA=output force/input force= 320/80=4
The sideways force one feels when a car turns sharply is often called
a.)thrust force
b.)angle force
c.)centrifugal force
d.)positive force
c.)centrifugal force
When two or more forces act to balance each other out, the condition is called
a.)equilibrium
b.)static recoil
c.)gravitational balance
d.)concurrent forces
a.)equilibrium
Two balls of the same density, one large and one small, roll toward each other at the same speed. When they collide, what will happen to the larger ball?
a.)it will be propelled backward
b.)it will jump over the smaller ball
c.)it will continue forward
d.)it will stop
c.)it will continue forward
*the lager ball will knock the smaller ball backwards
Using the same image as the previous question, if gear D has twice the diameter of C, what is the mechanical advantage of D? How many revolutions will C make for every revolutions of D?
a.)1/2
b.)1/4
c.)2/7
d.)3/4
a.)1/2
*MA=teeth output/teeth input=24/12=2
The smaller gear has 12 teeth and the larger gear has 24 teeth. If the small gear turns 12 times, how many revolutions will the larger gear make?
a.)2
b.)144
c.)6
d.)24
c.)6
*half of 12 turns is 6 turns
The power need to move 550 pound one foot over the period of one second is commonly called
a.)joule
b.)watt
c.)torque
d.)horsepower
d.)horsepower
Jack needs to pull a truck for 1 minute. The truck weighs 115.5 tons. What's the minimum number of horsepower necessary?
a.)3hp
b.)7hp
c.)21hp
d.)420hp
b.)7hp
115.5
2,000=231,000lbs
Divide 231,000/33,000(a single horsepower can move per minute)= 7hp
An elevator motor requires 5,968 watts to move the elevator. What is the horsepower of the electric motor operating the elevator?
a.)7
b.)8
c.)13
d.)746
b.)8
*divide 5,968/746=8
a.)1 in
If the Vat A is pressurized to move the liquid level down 1 inch, how much will the water level in the other vat rise, assuming that they are the same size?
a.)1 in
b.)2 in
c.)5 in
d.)7 in
Imagine a diver practice diving at a 20ft depth in a diving pool. Where is the water pressure greatest?
a.)Where the diver is
b.)Halfway between the bottom and surface
c.)It doesn't matter, water pressure is always equal
a.)Where the diver is
*water pressure increases by .43lbs per pound
Two identical enclose containers of liquid are connected by a pipe. If one side receives 12 lbs of force, how much will the other side receive due to the connecting pipe?
a.)1 lbs
b.)6 lbs
c.)12 lbs
d.)unknown
c.)12 lbs
Imagine you're using a pulley system to lift a box that weighs 100 lbs, but the pulleys are only 50% efficient.How many pounds of force are you actually putting into moving the box?
a.)75
b.)150
c.)200
d.)10
c.)200
*100/.50=200
An engine produces 90hp, and is 90% efficient. So how much horsepower is being lost because of inefficiency?
a.)90
b.)10
c.)110
d.)9
b.)10
*
90/.90=100
100-90=10
A man is trying to lift a large package. The package weighs 200lbs. If he exerts 80 lbs of force, will he be able to move the package upward?
a.)Yes because he has double the strength to lift the package
b.)Yes because he has the mechanical advantage to carry the package upward
c.)No the man will not be able to lift the package upward with 80 lbs of force
d.)No there is not enough information to know what the man is using to lift the package
c.)No the man will not be able to lift the package upward with 80 lbs of force
Say you are at work and you are using a staple to staple paper together. You are holding the front part of the staple to staple to the papers together. Which class of lever are you using?
a.)First class
b.)Second class
c.)Third class
b.)Second class
You are hammering a nail through a piece of wood, you are making sure you are holding the hammer the right way by holding the bottom of the hammer to grip it correctly to the strike the nail. Which class of lever are you using?
a.)First class
b.)Second class
c.)Third class
c.)Third class
If a rock climber expended 660 newtons up a 30 meters cliff, how much work did he exert?
a.)22 J
b.)690 J
c.)690 N
d.)19,800 J
d.)19,800 J
multiply 660
30=19,800 J
A child uses 3.5N to throw a ball into the air about 2.3 meters, how much work has she achieved?
a.)1.2 J
b.)5.8 J
c.)8.05 J
d.)1.521 J
c.)8.05 J
multiply 3.5
2.3=8.05 J
What the mechanical advantage of a wedge were the length is 21 and the width is 3?
a.)7
b.)6
c.)10
d.)4
a.)7
*MA=l/W
21/3=7
A wedge is 14 inches in length, and the mechanical advantage is 7. What is the width of the tool?
a.)8
b.)2
c.)9
d.)5
b.)2
*MA=L/W
7/14=W
2=W
On a incline plane, the length is 15 and the height is 5. What is the mechanical advantage?
a.)7
b.)20
c.)18
d.)3
d.)3
*MA=L/H
MA=15/5
MA=3
A truck ramp is used for its mechanical advantage, if it's 18 meters long and 3 meters high, what is the mechanical advantage of this inclined plane?
a.)4
b.)8
c.)6
d.)10
c.)6
**MA=L/H
MA=18/3
MA=6
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