MECHANICAL CONCEPTS Test

TECH Mechanical Concepts

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TECHNICIAN OCCUPATIONS SELECTION SYSTEM MECHANICAL CONCEPTS PRACTICE TEST JULY 2004 EEI © Copyright Statement The set of electronically linked documents that you are currently viewing or reading over the Internet/World Wide Web belong to or were created, posted or otherwise made available by or with the permission of EEI. The contents of all such material located at or available on this Internet site, however referred to (such as EEI's Internet homepage, Web page, Web site, site, etc.) are copyrighted by EEI unless otherwise indicated. Copyright is not claimed as to any part of an original work prepared by a United States federal or state government officer or employee as part of that person's official duties. All rights are reserved by EEI, and no content located at or available on this site may be reproduced, downloaded, disseminated, published, or transferred, in any form or by any means, except with the prior written permission of EEI. Consistent with their membership status and the mission and purpose of EEI, members of EEI and, pursuant to the appropriate Terms and Conditions of Use and/or License Agreement, subscribers to EEI Electric Subscriptions may download content from EEI's site for their own use on a single computer. However, no part of such content may be otherwise or subsequently reproduced, downloaded, disseminated, published, or transferred, in any form or by any means, except with the prior written permission of EEI. For full information, please see EEI's Copyright & Policy Statement. These practice tests are for informational purposes only, and are not a guarantee that an applicant will pass a related test.

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TECH Mechanical Concepts

Page 2 of 19 MECHANICAL CONCEPTS

The Mechanical Concepts selection test measures a candidate's ability to understand mechanical principles. Each question contains a pictorial description of a mechanical situation, a question and three possible answers.

MECHANICAL CONCEPTS PRACTICE TEST This practice test is similar in content and structure to the real selection test. We recommend that you time yourself while taking the practice test to get a feel for how much time you will have to complete the real selection test. It may be to your advantage to complete all practice test questions. Answers and explanations for the practice test questions are provided at the end of the practice test. You should consult these answers only after completing all the practice test questions. Directions This is a test of your ability to understand mechanical concepts. Each question has a picture, a question, and three possible answers. Read each question carefully, study the picture, and decide which answer is correct. This practice test has 26 questions and should take you 13 minutes to complete.

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TECH Mechanical Concepts

Page 3 of 19 MECHANICAL CONCEPTS PRACTICE TEST

1. Which of the two wagons of equal weight (A or B) requires less force to pull? (If equal, mark C.)

2. Which of the two persons (A or B) will have to exert more effort to pull the box up? (If equal, mark C.)

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3. In which direction will gear Z spin if wheel X is spinning clockwise? (If both, mark C.)

4. If the car and truck are moving at the same speed, in which direction will the truck tend to go when it collides with the car at point X?

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5. On which side of the pipe (A or B) would the water speed be slower? (If equal, mark C.)

6. Which of the two chairs (A or B) with equal size and weight would be easier to drag across the room? (If equal, mark C.)

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7. Two tanks with different capacities contain the same amount of oxygen, 500 liters. In which of the tanks (A or B) will the gas pressure be greater? (If equal, mark C.)

8. A spark ignites the gas within the cylinder . In which direction (A or B) would the piston move? (If it will not move in either direction mark C.)

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9. Among this arrangement of three pulleys, which pulley (A, B or C) turns fastest?

10. In the picture below which of the angles (A, B or C) is braced more solidly?

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11. An object is thrown in the air. At which point (A, B, or C) will it be traveling slowest?

12. In which of the two figures (A or B) will the person require less force to lift a 50 pound weight? (If equal, mark C.)

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13. Which of the three switches (A, B, or C) , if broken and cannot be closed, will prevent the flow of electricity in the terminal?

14. Which switch (A, B, or C) should be closed to light the bulb?

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15. The weight of the box is being carried entirely on the shoulders of the two men shown below. Which of the two men is carrying more weight? (If equal, mark C.)

16. Which of the two saws (A or B) will allow you to cut faster? (If equal, mark C.)

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17. The water in container A contains 50% salt. The water in container B contains 20% salt. In which of the two containers (A or B) is the object more likely to float? (If equal, mark C.)

18. Given two water towers with identical water tanks and identical amounts of water in each tank, which tower (A or B) will have a greater water pressure coming out of the hose? (If equal, mark C.)

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19. Which situation (A or B) requires more force to load the barrel onto the truck? (If equal, mark C.)

20. In which of the two tanks (A or B) will water that is boiled to the exact same temperature cool faster? (If equal, mark C.)

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21. In which of the three positions (A, B, or C) will it be easiest to accurately measure the amount of water in the bucket?

22. Which of the two trucks (A or B) carrying the same amount of weight is less likely to turn over when reaching a sharp curve? (If both, mark C.)

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23. Suppose that a valve between the bucket and hose has been closed. If the valve opened, which of the pictures (A or B) would show a more accurate representation of the way in which the water will flow? (If neither, mark C.)

24. Which of the two identical objects (A or B) will travel a greater distance when the compression springs are released? (If equal, mark C.)

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25. Which point on the wheel (A or B) is going to be traveling a greater distance when the wheel turns? (If equal, mark C.)

26. Container A contains 200cc pure water and container B contains 200cc cooking oil. Assume an object is thrown into either of these two containers; in which container is the object more likely to float? (If equal, mark C.)

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End of Practice Test Check your time and move on to the practice test answers and explanations.

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ANSWERS AND EXPLANATIONS 1. The correct answer is B. In both pictures, the man has to overcome gravity in order to pull the wagon up the hill. As the hill becomes less steep, less force is required to overcome gravity. 2. The correct answer is B. In picture A, we have two pulleys, whereas in picture B we have a single pulley. When you have a single pulley that does not move (as in picture B where the pulley is attached to the ceiling) the force needed to lift the weight does not change. In picture B the pulley allows the person to use his own weight to pull downward on the rope and pull the box. In picture A, the two pulleys distribute the weight of the box equally among the two sides of the rope, half of the weight on each side. This means that the man in picture A has to apply only half the force to pull the box up. 3. The correct answer is B. Since gear X is turning clockwise, it will turn gear Y counterclockwise. Gear Y, turning counterclockwise, will turn gear Z clockwise, which is answer B. 4. The correct answer is C. This question deals with momentum. Momentum is a combination of weight and speed. It will determine the direction in which two colliding objects will go. The objects will move in the direction of the one with the higher sum of weight and speed. The truck and car are driving at the same speed. The truck, however is three times the weight of the car. Thus, after the collision, the truck will tend to continue in its original direction, toward point C. 5. The correct answer is B. The flow rate of fluids is the amount of fluid that passes through the pipe in a given time. As a rule, a single pipe has the same flow rate from beginning to end, even if the width of the pipe changes. The flow rate going into the pipe must be equal to the flow rate coming out of it. The pipe is wider on the right side than it is on the left side. In order to compensate for the changes in the width of the pipe and maintain an equal flow rate, the water speed would be slower in the wider section of the pipe. 6. The correct answer is B. This question deals with friction resistance. Friction resistance is the resistance of one surface (e.g., a floor) to the movement of another surface (e.g., a chair). The floor in picture B is smoother in comparison to the one in picture A. Thus, friction resistance in picture B is smaller, making it easier to drag the chair across the floor. 7. The correct answer is B. In this question you have two gas containers. Container A can contain 1,000 liters and container B can contain 750 liters. When the same amount of gas is put into two different sizes of containers, the pressure of the gas in the smaller container will be greater. 8. The correct answer is A. The ignition of the gas raises the temperature, which increases the pressure of the gas. The increased pressure of the gas forces the piston upward. 9. The correct answer is A. Pulley A has the smallest circumference and therefore is going to turn faster than the other larger pulleys. 10. The correct answer is C. Pole C covers more area of the hole, so it is more solidly braced.

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11. The correct answer is B. At the height of the arc, the ball has no upward or downward momentum; thus, point B would be the point where the object's speed is slowest. 12. The correct answer is B. This question deals with levers. A lever is a simple machine that uses a fulcrum (point of support) to increase the effect of effort. The fulcrum, or point of support, is immovable. The area to the right of the fulcrum is called the resistance arm and the area to the left of the fulcrum (where the weight is placed) is called the effort arm. As a rule, when the ratio of the effort arm to the resistance arm is greater, the amount of force needed to lift an object decreases. Looking at the two drawings you can see that person A has a short effort arm and a long resistance arm, and person B has a short resistance arm and a long effort arm. Therefore, person B requires less force to lift the weight. 13. The correct answer is C. Electricity must be sent along a path of a closed circuit. If switch A is broken, electricity can flow through switch B. If B is broken, electricity can flow through switch A. However, if switch C is broken, electricity does not have an alternate route, and thus will not be able to flow in the circuit. 14. The correct answer is C. In order for the bulb to light, electricity must flow in a closed circuit. The only way electricity can flow from pole to pole is by closing switch C. 15. The correct answer is B. For the weight to be equally distributed, the object being carried needs to be centered. In the present question, the weight is not centered, rather it is closer to man B. Thus, man B is carrying more of the load. 16. The correct answer is B. Saw B is larger; thus, it has a larger radius. One revolution of the saw will cover a greater distance and will cut faster. 17. The correct answer is A. The density of of the water in container A containing 50% salt is greater than that of the water in container B containing only 20% salt. The likelihood of an object to float increases as the density of the water increases. Therefore, the object is more likely to float in container A than in container B. 18. The correct answer is B. There are two downward forces operating to push the water down the hose. The first is gravity, that pulls the water down with more force as the height of the tower increases. The second is the weight of the water, or the column of water, that is pressing the water down with greater force in the taller tower. 19. The correct answer is B. The force required to lift a given weight is dependent upon the length of the ramp. Longer ramps require less force, but force needs to be sustained over a longer distance (the distance of the ramp). Shorter ramps, on the other hand, require more force over a shorter distance. 20. The correct answer is A. When more of a liquid's surface is in contact with air, it cools down faster.

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21. The correct answer is A. Measuring liquids is easiest on leveled surfaces. On unleveled surfaces (such as shown in pictures B and C) water tends to shift from the highest to the lowest point, making measurement much more complicated. 22. The correct answer is B. When the weight of cargo is evenly distributed (such as in truck B) and does not shift around during travel, a vehicle is more stable on the road. On the contrary, a vehicle with an uneven distribution of weight (such as the truck in A) is less stable. Such a vehicle is more likely to turn over when reaching a curve in the road. 23. The correct answer is B. As a rule, water always seeks its own level. Thus, the water in the bucket will migrate until it is at exactly the same level as the water in the hose. 24. The correct answer is B. When a spring is compressed (or stretched) a force, called restoring force, will push to return the spring to its normal length. The more compressed (or stretched) the spring is, the larger this pushing force. The spring in picture B is more compressed than the one in picture A. This makes the force pushing the object (resulting from the restoring force) in picture B larger than the one in picture A. 25. The correct answer is A. The further from the center of the wheel a point is, the greater distance it will travel. 26. The correct answer is A. When put into liquid, objects are more likely to float the heavier or more dense the liquid. Since water is a more condensed liquid than oil, an object is more likely to float in the container that contains water.

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