= WHW-CH1 X | @ MI60ch1 HW.pdf X @ 2ag HCHW Ch 1 (14) x WA 2ag HW Ch 1(20) - Physics 280 X | + a 3 ktop%20user/Downloads/2ag%20HCHW%20Ch%201 9%20(14)%20(1).pdf 1.C. Afriend says he was given a ticket for speeding on the freeway. When you asked him how fast he was going he says 100. What's wrong with his statement? 2.4. 1 centimeter = 6.2137 X 107 miles. Since every conversion factor has two equations then what is the other one? HELP: Put the 1in front of miles. 3.E a. What is your height in mm units. b. What is your mass-weight in grams if you are given that 1 kg = 2.20 Ibs. 4.E. a. Fillin the two blanks with numbers. mm =1m and 1mm = m b. Fill in the two blanks with numbers: 1KJoule=____ Joules and __ Kloule =1 Joule S.E. a. Suppose you are given that 1mile = 5280 ft. How many square feet are in 1 square mile. ANS: 2.8 x 107 in standard scientific notation NOTE: If this was a WebAssign problem the student would have to enter it as 2.8e7 b. If 100cm = 1m then 1 m = cm? 6.E. a. The prefix \"kilo\" in the metric system means multiply by so 1 kilocalorie equals calories. Since conversions can always be stated two ways, this means that 1 calorie also equals_____kilocalories. b. The prefix \"micro\" in the metric system means multiply by so 1 microliter equals liter. Since conversions can always be stated two ways, this means that 1 liter also equals microliters. 7.C. When using standard metric units like time in seconds, mass in kilograms, length in meters, sometimes the numbers are not the \"natural units\". Natural units are units that make the numbers in your answer look the nicest and simplest. For instance, it is more natural to say | bought a shirt for $10 rather than 1000 cents. A snail can crawl 6 feet in 3 hours. a. Calculate the snails speed in units of centimeters/minute. b. Calculate the snails speed in units of miles/day. c. Which is the more natural unit to characterize a snail's speed? 8.E. You want to paint a wall in your room measuring 14 feet x 9 feet with a thickness of 1 millimeter. If paint at HomeDepot costs $12 each gallon, then what will be the cost of your project in units of dollars (round to the nearest dollar). Use the fact that 1 gallon=0.134 ft3 and 2.54 cm=1inch. ANS: 37 9.E. A scientist has discovered a new atom called Scottonium. It has a density of 7.51 g/cm* and the mass of one atom Is 4.62 X 1072*mg. Where mg is short for milligram. a. If the atoms are spherical and tightly packed, then what volume of one Scottonium atom in units of [m*] ? ANS: 6.15e 33 HELP: Use dimensional analysis. You don't need to know anything about basic chemistry. b. What is the distance between the centers of two adjacent atoms in units of [em]. ANS: 2.27e -9 == WHW-CH1 X | @ M160 chl HW.pdf X @ 2agHCHW Ch 1(14) x | WA 2agHWCh1(20)-Physics2ec X | + sktop%20user/Downloads/2ag%20HCHW%620Ch%201%20(14)%20(1).pdf | 4 HELP: See picture and Viphere = ST 10.8. a. A physics formula has the form v = Af where v is speed in units of ::::; and f is frequency in units of 1/second. For this formula to be dimensionally consistent, what are the units of ? b. A physics formula has the form I = ea AT * where I is intensity in units of Watts/meter?, e is unitless, A is area in units of meter? and T is temperature in units of Kelvin. For this formula to be dimensionally consistent what are the units of o ? ANS: Watt/m?*: Kelvin* 11.9. We will learn in Chapter 6 that the force F necessary to keep an object moving in a circle is directly proportional to the square of the object's speed, v2, a. As v increases what happens to w2 (does it increase or decrease)? What then happens to F (i.e., does it increase or decrease)? b. Write an equation that relates the two variables F, v? using an unknown constant k. c. Acar moving around a circular track ata speed of 20 mile/hour requires the frictional force between its tires and the ground to be 500 pounds. What is the value and units of the proportionality constant. What is the equation that relates the two variables F, v using an unknown constant k. d. Ifacars speed is 15 mile/hour whatis the value of the force? 12.9.E. Two variables may be directly proportional or inversely proportional. To say that y is inversely proportional to x means that as one. variable goes up the other variable goes down and vice versa. Yy g 5 i 1 y is inversely proportional to x is symbolized y = This means there is some constant k so that the equation relating y to x is given by k Y we will learn in Chapter 14 that brightness of light called its intensity / is inversely proportional to the square of the distance r2 from the light source. a. Asr increases what happens tor? (does it increase or decrease)? What then happens to I (i.e., does itincrease or decrease)? i b. Write an equation that relates the two variables I, r? using an unknown constant k. . The intensity froma light source is 50 Watts/meter? when observed from 2 meters away. What is the value and also the units of the proportionality constant. What is the equation that relates the two variables I, 2 using your value for k. = WHW-CH1 X | @ MI60 chl HW.pdf X @ 2ag HCHW Ch 1(14) % W Zag W Ch 1 (20) - Physics 280 X T F )p%ZOuser/Dowr\\lcads/Zag%ZOHCHW%20Ch%201 9%20(14)%20(1).pdf d. What intensity do you expect to measure at 10 meters away? ANS: 2 13.C. WebAssign has a different way of putting in answers in scientific notation than what we are used to in algebra class. Algebra Class How to input on Notation WebAssign 2,57 x 10* 2.57e33 9.0 X107 9.0e =11 10% 125 So that you don't get input errors on scientific notation when doing WebAssign homework or exams answer the following: 2. How would you input 10** on WebAssign? b. How would you input 3.77 X 10722 on WebAssign? 14.E. Since your answers on a WebAssign exam are to be within =2.5% of the correct answer it is important you don't round calculations too eorly. This can occur especially when you have parts of a problem that depend on early parts. Lets explore this below. A problem has 3 formulas: a = Vb and = % and d=c+453 Question: 1f b = 5.00 then find d Joe-Student does the following, a = \\/5.00 = 2.236077977 which he then rounds to 2:2 = % 1270170592 which he then rounds to 1.3 +453 = (13 +4.53=622 The following is the computation done by the testing program a = /500 = 2236077977 which then s rounded to 223608 22308 _ 1 5011001390 which then then rounded to 1.29110 i d = & +4.53 = (1.29110)" +4.53 = 6.196939210 which then is rounded to 6.20 The correct answer is 6.20 but Joe-Student is off by a little. Does he get credit? WebAssign takes 2.5% of 6.20 = 0.155 hence judges the range of \"good answers\" as 6.20-0.155