Physics Practice Exam 1 Answer Key

Discussion Section Problems Answer Key (Practice Exam 1) Each Questions 6.7 Points! Please grade your paper. I will post a video for the solutions. You do not have to turn in this paper. 1) The Syst`eme International (SI) of units is based on meters, grams, and seconds. a) True b) False 2) The speed of sound is measured to be 344 m/s on a certain day. What is this in km/h? a) b) c) d) 1350 km/h 1240 km/h 1130 km/h 1540 km/h 3) The speed limit on certain interstate highways is 40 miles per hour. What is this in feet per second? a) b) c) d) e) 55.6 ft/s 37.8 ft/s 58.7 ft/s 48.5 ft/s 74.3 ft/s 4) The length and width of a rectangular room are measured to be 4.189 ± 0.005 m and 4.060 a) b) c) d) ± 0.005 m. Calculate the area of the room. 2 17.01 m 15.11 m2 16.34 m2 1600 m2 5) What is the sum of the measured values 23.0 s + 18 s + 16.20 s + 4.002 s? (Express your answer to the correct number of significant figures) a) b) c) d) 61.202 s 61 s 62 s 61.3 s Discussion Section Problems Answer Key (Practice Exam 1) 6) A ladder 6.75 m long leans against the side of a building. If the ladder is inclined at an angle of 67.5¡ to the horizontal, what is the horizontal distance from the bottom of the ladder to the building? a) b) c) d) e) 4m 2.58 m 2.35 m 1.99 m 4.33 m 7) A good-quality measuring tape can be off by 0.43 cm over a distance of 31 m. What is its percent uncertainty? a) b) c) d) e) 0.011 0.032 0.024 0.018 0.014 8) If your speedometer has an uncertainty of 3.0 km/h at a speed of 88 km/h, what is the percent uncertainty? (Express your answer to the correct number of significant figures and proper units. Use unrounded values in your calculations.) a) b) c) d) e) 2.54 km/h 3.0 km/h 3.4 % 3.41 % 3.4 km/h 9) What is the area of a circle 3.076 cm in diameter? (Express your answer to the correct number of significant figures) a) 6.332 cm2 b) 5.768 cm2 c) 8.432 cm2 d) 7.431 cm2 e) 7.400 cm2 Discussion Section Problems Answer Key (Practice Exam 1) 10) The sides of a small rectangular box are measured to be 1.70 ± 0.01 cm, 2.05 ± 0.04 cm, and 3.9 ± 0.1 cm long. Calculate its volume and uncertainty in cubic centimeters. (Express your answers to the correct number of significant figures.) a) volume 16 cm3, uncertainty 0.6 cm3 b) volume 15 cm3, uncertainty 0.7 cm3 c) volume 14 cm3, uncertainty 0.6 cm3 d) volume 16 cm3, uncertainty 0.7 cm3 e) volume 14 cm3, uncertainty 0.7 cm3 11) Suppose your bathroom scale reads your mass as 61 kg, with a 6% uncertainty. What is the uncertainty in your mass? (Note that uncertainties should be reported to one significant figure.) a) 3 kg b) 4 kg c) 5 kg d) 6 kg e) 1 kg 12) State the number of significant figures in each of the following. (a) 90 (b) 3.9 104 (c) 3.90 104 (d) 9.03 104 (e) 9.030 104 (f) 0.0039 (g) 0.093 (h) 0.0309 Discussion Section Problems Answer Key (Practice Exam 1) 13) Below is the calculator result for the operation indicated. Chose the answer to the correct number of significant figures for this calculation, using the rules for significant figures. 3.82 + 10.586 = 14.406 a) 14.40 b) 14.5 c) 14.4 d) 14 e) 14.406 f) 14.41 14) In a laboratory, a researcher measures time using a stopwatch and finds that the time is between 10.54 s and 10.63 s. What should he report for the measured time and its error? (Enter your answers to at least two decimal places.) a) 10.585±0.045 b) 10.585±0.09 c) 10.54±0.040 d) 10.63±0.5 e) 11.00±0.045 15) During a visit to New York City, Lil decides to estimate the height of the Empire State Building (see figure below). She measures the angle » of elevation of the spire atop the building as 21¡. After walking x = 8.50 7 102 ft closer to the iconic building, she finds the angle to be 26.2¡. Use Lil's data to estimate the height h of the Empire State Building. (Enter your answer to at least the nearest foot.) a) 1483.9 ft b) 2143.5 ft c) 1865.3 ft d) 2433.9 ft e) 1932.8 ft