PHYS 1410 Exam1

Name: ____________________________________ Clicker #___________ Physics 1410 First Exam - Rework __________________________________________________________________________________________ No Work. No Credit. Even if you have the correct answer. If you want FULL credit, answer the question that I actually ASKED, and explain, show your work, or otherwise justify your answer as needed. If you don’t want full credit, feel free to ignore these instructions. :) You can use psychic dolphins this time. __________________________________________________________________________________________ 1 st area (basic principles 26 points) 1. (1-pt each) For the following values, tell me how many sig figs they have. a) 1.25 m 3 sig figs b) 2.34 x 10 6 m/s 3 sig figs c) 0.00042 N 2 sig figs d) 2,400,000 ambiguous, could be within the range of 2-7 sig figa 2. (2-pts each)Solve the following math problems. (You must give the answer with the correct units, and significant figures) a) 2.0629 lbs 3.8 ¿ 2 ______________ b) 322.6 m ( 3.04 s + 27 s ) ______________ c) 346.63 g − 346.42 g ______________ 3. (1-pt each)Give the proper SI unit for the following: a) Length Meters b) Mass Kilograms c) Time Seconds d) Electric Current Amps e) Force Newtons

4. (5-pts) Given that an inch is 2.54 cm, and a foot is 12 inches and there are 3600 seconds in an hour. Show your steps to convert the following: 2200 ft/s -- convert this into m/s and then into km/hr (I am assuming you know the meanings of the prefixes k, and c) 2200 ft/s = 670.56 m/s 1 ft = 12 inch 1inch=2.54 cm 1 meter= 100 cm 12inch x2200 = 26400 inch 26400 inch x 2.54cm = 67056cm 67056/100= 670.56 m/s 3600 sec= 1 hr 670.56 m/s x3600 s= 2414016 2414016/100= 24140.16 km/hr 5. (2-pts each) If you took two measurements trying to find the value of gravity, the first measurement is 8.75 m/s 2 and the 2 nd measurement was 9.38 m/s 2 a) Give the percent difference between your 2 measurements. b) Give the average value of your measurements. c) If the real value of gravity is 9.80 m/s 2 give the percent error in your average measured value.

3 rd area (Motional definitions 20-pts) 7. An ionic rocket is trying to leave the solar system. This rocket has a very low thrust but is able to maintain it for a very long time (and use very little fuel compared to standard rockets) If the thrust gives our vessel an acceleration of 1.25 x 10 -4 m/s 2 answer the following questions. a) If we assume the vessel leaves earth’s orbit with an initial velocity of v o and we can assume it maintains a constant acceleration of a along its path, write out an expression for the distance the vessel has traveled (D) after some time t b) If the initial velocity was 0 m/s when it left earth’s orbit. And it had traveled 1.25 x 10 11 m as it passed Mars’ orbit, tell me how long this took (convert your answer to days) c) The distance from earth to Pluto is 7.5 billion km. If this vessel goes by Pluto, tell me how long before it gets there (For this one I want you to convert it to years) d) Write out an expression for the final velocity of the vessel in terms of things you know (there is more than one right answer here) e) Calculate the speed of the vessel as it passes Pluto.

4 th area (Forces 22 pts) 8. (2-pts each) Define each of these forces. (explain how they act, and what causes them) a) N - b) W - c) f k - d) f s - e) T - f) F A - (10-pts) James is trying to pull his sofa up a ramp. While James is dragging the sofa up the slope at a constant speed, show me what forces are acting on this sofa. (Draw arrows for each of the forces and label them. Then below describe these forces.