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ASVAB Mechanical
Comprehension
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: b.)4: c.)1: d.)2:1 ✔ Ans - b.)4: 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 ✔ Ans - b.)Multiplies force and changes direction Tension can best be called a.)A weight b.)A force c.)A movement d.)A direction ✔ Ans - 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 ✔ Ans - 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 ✔ Ans - *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 ✔ Ans
- 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 ✔ Ans - a.)Torque Which of the following is NOT a unit of power? a.)Watt b.)Horsepower c.)Volt-ampere d.)Newton ✔ Ans - 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 ✔ Ans - *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.
vf = 0 + 32*1. 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 ✔ Ans - 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 ✔ Ans - 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 ✔ Ans - 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 ✔ Ans - b.)compound
A force that pushes materials together. a.)effort b.)compression c.)resistance d.)compound ✔ Ans - b.)compression In a lever, the point where you apply force. a.)flexibility b.)effort c.)friction d.)kinetic ✔ Ans - b.)effort In a lever, the distance from the force to the fulcrum. a.)effort arm b.)load arm c.)tension d.)potential ✔ Ans - a.)effort arm Energy in moving electrons a.)potential energy b.)electrical energy c.)resistance d.)effort force ✔ Ans - b.)electrical energy The ability of a material to bend without breaking. a.)effort force b.)flexibility c.)potential d.)resistance ✔ Ans - b.)flexibility The force that resists the relative motion of two surfaces in contact. a.)effort force b.)friction c.)gravity d.)load ✔ Ans - b.)friction An attractive force between objects
Energy is a.)The power of motion b.)The application of force c.)The capacity to do work d.)The opposition of weight ✔ Ans - 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 ✔ Ans - 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 ✔ Ans - 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 ✔ Ans - 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 ✔ Ans - 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 ✔ Ans - 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 ✔ Ans - 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: b.)4: c.)2: d.)1:2 ✔ Ans - a.)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 ✔ Ans - d.)Force exerted on a object due to gravity
d.)P=w/t ✔ Ans - b.)F=ma force equals mass times accelatration What's the formula of pressure? a.)P=f/a b.)F=ma c.)W=fd d.)P=w/t ✔ Ans - 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 ✔ Ans - b.)magnetism What's the formula of work? a.)P=f/a b.)F=ma c.)W=fd d.)P=w/t ✔ Ans - c.)W=fd What's the formula of mechanical advantage? a.)P=f/a b.)F=ma c.)W=fd d.)MA=R/E=OF/IF ✔ Ans - 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=ma c.)W=f*d d.)MA=R/E=OF/IF ✔ Ans - 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=fd d.)MA=R/E=OF/IF ✔ Ans - 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 ✔ Ans - 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 ✔ Ans - 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 ✔ Ans - c.) metal spoon
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. b.) c.) d.)24.75 ✔ Ans - a.)23. *MA=output force/input force =7,406/308.6= 23. 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 ✔ Ans - 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 ✔ Ans - 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 ✔ Ans - 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.) b.) c.) d.)1,800 ✔ Ans - d.)1, 6003=1, 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.) b.) c.) d.)410 ✔ Ans - c.) 6002/3= 2/3= 1/2=. 400+5= 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 ✔ Ans - b.)320rpm 48/12= 4 804=
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 ✔ Ans - a.)4.2ft 200x=(803)+(605)+(50*6) 200x=240+300+ 200x= x=4. 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 ✔ Ans - c.)4 feet *MA=output force/input force= 320/80= 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 ✔ Ans - 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 ✔ Ans - 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 ✔ Ans - 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/ b.)1/ c.)2/ d.)3/4 ✔ Ans - a.)1/ *MA=teeth output/teeth input=24/12= 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.) b.) c.) d.)24 ✔ Ans - c.) *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 ✔ Ans - d.)horsepower
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 ✔ Ans - 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.) b.) c.) d.)10 ✔ Ans - c.) *100/.50= An engine produces 90hp, and is 90% efficient. So how much horsepower is being lost because of inefficiency? a.) b.) c.) d.)9 ✔ Ans - b.)
90/.90= 100-90= 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 ✔ Ans - 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 ✔ Ans - 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 ✔ Ans - 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 ✔ Ans - d.)19,800 J multiply 66030=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 ✔ Ans - c.)8.05 J multiply 3.52.3=8.05 J What the mechanical advantage of a wedge were the length is 21 and the width is 3?
