Important: This test consists of 16 multiple choice problems, each worth 6.25 points.

Transcription

1 Physics 214 Exam 1 Spring 2005 Fill in on the OPSCAN sheet: 1) Name 2) Student identification number 3) Exam number as 01 4) Sign the OPSCAN sheet Important: This test consists of 16 multiple choice problems, each worth 6.25 points. Instructions: For each problem, choose the one answer that is correct or most nearly correct. Make a small mark, for your eyes only, near the letter of your choice. After you finish and check all the multiple-choice problems, transfer your answers to the computer sheet. Then, until you hand in the computer sheet, turn the sheet over and leave it face down. Only answers on the computer answer sheet will be graded. As your OPSCAN answer sheet will not be returned, record the answers on the test paper that you will keep. The correct answers will be displayed on the course web page, and you can find your score for this exam on CHIP. This is a closed book exam, but a crib sheet is provided. You may also use a calculator. Any form of cheating will result in severe penalties, which will include a score of zero for this exam and may result in a grade of F for the course and referral to the Dean of Students. All electronic devices must be securely put out of sight and may not be touched during the exam. All cell phones and pagers must be turned off. The only items you are allowed are the exam, the opscan sheet, a pencil and a calculator Page 1

2 FORMULAE AND CONSTANTS Conversion Factors 1 inch = 2.54 cm 1 ft = 30.5 cm 1 m = ft 1 km = miles 1 mile = 5280 ft 1 nautical mile = miles 1 kg = lbs (where g = 9.8 m/s 2 ) Equations s = d/t s = d/δt v = d/δt (vector) a = Δv/Δt (vector) v = v 0 + at d = v 0 t + ½at 2 d = ½(v + v 0 )t F = ma (vector) W = mg Page 2 Constants g = 9.8 m/s 2 π = 3.14

3 1. Your new weed-cutter requires, as fuel, a gas-to-oil mixture of 20-to-1 (20 parts of gas mixed with one part of oil). You have 1/3 of a gallon of gas. How much oil, in gallons, should you add to make it all into fuel for the weed-cutter? A) 1/63 B) 1/30 C) 3 D) 1/60 E) 1/20 2. An auto moves 10 meters in the first second of travel, 10 more meters in the next second and 10 meters during the third second. The acceleration of the auto in m/s 2 is A) 3.33 B) 9.8 C) 30 D) 10 E) Zero. 3. A car travels a distance of 80 km. For the first 30 minutes it is driven at a constant speed of 80 km/hr. The motor begins to vibrate and the driver reduces the speed to 40 km/hr for the rest of the trip. The average speed for the entire trip is: A) 60.0 km/hr. B) 53.3 km/hr. C) 50.0 km/hr. D) 47.5 km/hr. E) 40.0 km/hr. 4. If the braking distance for your car at a certain speed is 200 ft and, after reacting to a situation, you have managed to stop your car in 4.0 s, then the magnitude of the acceleration was A) 12.5 ft/s 2. B) 25 ft/s 2. C) 32 ft/s 2. D) 50 ft/s 2. E) 75 ft/s 2 Page 3

4 5. Which of the curves in the figure best shows the speed of an object falling from rest without air friction? A B C D 6. ( Ignore air friction for this problem.) Two identical balls are thrown simultaneously from the top of a very tall cliff. Ball A is thrown downward with an initial velocity of 6 m/s, while ball B is thrown straight upward with an initial velocity of 9.8 m/s. After one second has elapsed, the A) acceleration of ball A is upward B) velocity of ball B is zero. C) the acceleration of ball A is greater than that of ball B. D) velocity of ball A is 9.8 m/sec 2. E) acceleration of both balls is zero. 7. A stone is thrown upward from a bridge at a speed of 10 m/s. It narrowly misses the bridge on the way back down, and hits the water at 30m/s. The bridge is about A) 3 m high. B) 10 m high. C) 30 m high. D) 40 m high. E) 20 m high 8. The force that accelerates a car on a level road is exerted by which object? A) Motor. B) Gears. C) Rear axle. D) Drive shaft. E) The road. Page 4

5 9. A 5.0 kg block on a smooth horizontal surface is acted upon by two forces: a horizontal force of 40 N acting to the right and a horizontal force of 10 N to the left. The acceleration of the block will be: A) 6.0 m/s 2 to the right B) 10.0 m/s 2 to the right C) 8.0 m/s 2 to the right D) 5.0 m/s 2 to the right. E) 4.0 m/s 2 to the right. 10. Your mass is 50 kg. Suppose you are standing on a scale in an elevator which starts moving up and increases its speed at the rate of 2 m/s every second. What would be the reading on the scale? A) 590 N B) 490 N C) 390 N D) 100 N E) All except one of the following require the application of a net force. Which one is the exception? A) to change an object from a state of rest to a state of motion. B) to maintain an object in motion at a constant velocity. C) to change an object's speed without changing its direction of motion. D) to maintain an object in uniform circular motion. E) to change an object's direction of motion without changing its speed. 12. A bullet is fired horizontally from a height of 4.9 m with a velocity of 680 m/s. How far away does the bullet land? A) 680 m B) 340 m C) 1360 m D) 170 m E) 800 m Page 5

6 13. Imagine you are in a rocket on earth that suddenly is ignited, producing an acceleration upward until it reaches a constant velocity on its way to outer space. While the rocket is accelerating upwards, which of the following statements is true? A) your weight remains the same B) your weight increases C) your weight decreases D) your mass increases E) your mass decreases 14. A car traveling with an initial velocity of 15.5 m/s accelerates at a constant rate of 3.0 m/s 2 for a time of 3.6 seconds. (a) What is its velocity at the end of this time? A) 26.3 m/s B) 18.5 m/s C) 10.8 m/s D) 22.1 m/s E) 19.1 m/s 15. If the number were converted into powers of ten notation, it should be written as A) 1.25 x 10 3 B) 1.25 x 10 2 C) 1.25 x 10 0 D) 1.25 x 10-2 E) 1.25 x A ball is thrown as a projectile with a horizontal velocity of 30 m/s and a vertical velocity of 30 m/s. At the highest point which of the following is true? A) The velocity is zero B) The acceleration is 0 C) The acceleration is 9.8 m/s 2 D) The acceleration is -9.8 m/s 2 E) The vertical velocity is -30 m/s Page 6

7 Answer Key 1. D 2. E 3. B 4. B 5. A 6. B 7. D 8. E 9. A 10. A 11. B 12. A 13. B 14. A 15. E 16. D Page 7