Physics 214 Practice Exam 1_A 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
FORMULAE AND CONSTANTS Conversion Factors 1 inch = 2.54 cm 1 ft = 30.5 cm 1 m = 3.281 ft 1 km = 0.621 miles 1 mile = 5280 ft 1 nautical mile = 1.1508 miles 1 kg = 2.205 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 average speed instantaneous speed instantaneous velocity acceleration force weight Page 2
a = v 2 /R F = mv 2 /R F = GM 1 M 2 /R 2 W = Fd P = W/t KE = ½ mv 2 PE = mgh PE = ½ kx 2 P = mv FΔt = P f P i = Δp F external = 0, Δp = 0 centripetal acceleration centripetal force gravitational force work power Kinetic energy potential energy potential energy momentum impulse momentum conservation Circumference = 2πR g = 9.8 m/s 2 G = 6.67 10-11 N m 2 /kg 2 π = 3.14159 ω = θ/t = Δθ/Δt α = Δω/t ω = ω 0 t + αt θ = ω 0 t + ½ αt 2 Torque = Fl = τ L = Iω τ = Iα τ external = 0, Page 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. A net force of 44N accelerates an object of mass 5kg to a speed of 8m/s. How much work in joules is done by the net force? A) 264 B) 160 C) 40 D) 352 E) 220 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. A girl on a sled with a total mass of 90kg starts from an elevation of 100meters. At the bottom of the run her speed is 30m/s. How much energy in joules was lost due to friction? A) 545 x 10 2 B) 477 x 10 2 C) 882 x 10 2 D) 966x 10 2 E) 356 x 10 2 Page 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. Two balls of the same mass are accelerated by different net forces. One ball gains a velocity twice that of the other ball. What is the ratio of the work done on the faster ball to the work done on the slower, W f /W s? A) 2 B) 1/4 C) 1 D) 4 E) 1/2 Page 5
9. 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 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) 0 11. Car A travels with speed v around curve number one, which has a radius r. Car B travels with speed 2v around curve number two, which has a radius 2r. What is the ratio of the two accelerations A/B? A) 2 B) 4 C) 1/2 D) 1/4 E) 1 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 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. A refrigerator weighing 1500 N is to be lifted onto a truck bed that is 1.0 m above the ground. When pushed up a slanting ramp 2.0 m in length a force parallel to the ramp of only 800 N is required to move it at constant velocity. Comparing the work involved in lifting the refrigerator straight up to the work in pushing it along the ramp, there is A) more work required when the ramp is employed. B) an equal amount of work is required in each case. C) less work required when the ramp is employed. Page 7
Answer Key 1. D 2. B 3. B 4. B 5. A 6. B 7. D 8. D 9. D 10. A 11. C 12. A 13. B 14. A 15. A Page 8