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Scientific Notation Scientific notation takes the form: M x 10 n M is some number between 1 and 9 n represents the number of decimal places to be moved – A positive n indicates that the number is large – A negative n indicates that the number is between 0 and 1
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Converting to Scientific Notation Move the decimal so that there is one number between 1-9 in front of the decimal. – If there is no decimal, it is located after the last 0 at the right side of the number. – If you move the decimal to the left the exponent is positive and if you move the decimal to the right the exponent is negative. Example 1: 750000000 = Example 2: 0.00000354 =
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Convert the following to scientific notation 869000000 = 50500 = 0.00907 = 0.576 = Convert the following to standard notation 8.23 x 10 3 = 7.12 x 10 -6 = 3.67 x 10 8 = 2.003 x 10 -2 =
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Significant Figures Measured quantities are always reported in a way that shows the precision of the measurement. – Precision is the degree of exactness of a measurement, how many decimal places an instrument can measure. Significant figures are digits in a measurement that are known with certainty. Accuracy is the extent at which a measurement approaches the true value.
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Degree of Precision
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Draw darts to show the following Good accuracy and good precision Good accuracy and poor precision Poor accuracy and good precision Poor accuracy and poor precision
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Significant Figures If the decimal is present start from the left side and start counting digits when you see a number from 1-9. If the decimal is absent start form the right side and start counting digits when you see a number from 1-9. Example 1: 0.000030050 = Example 2: 20500000 = Pacific Side Decimal is present Atlantic Side Decimal is absent
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Write the number of significant figures. 2005000 = 3.040 x 10 4 = 0.0004005 = 0.1 x 10 -9 =
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Calculations using significant figures When multiplying or dividing, round to the least number of significant figures in any of the factors. Example: 23.0cm x 432 cm x 19cm = 190,000cm 3 When adding or subtracting, round your answer to the least number of decimal places in any of the numbers that makes up your answer. Example: 123.25ml + 46.0ml + 86.257ml = 255.5ml
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Perform the following calculations expressing the answer in the correct number of significant figures. 2.005 m x1.2 m = 3.5 cm x 2.50 cm x 4.505 cm = 15.50 cm 3 3.2 cm = 2.004 m/s + 14.3 m/s = 150 ml – 23.5 ml =
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International System of Units Based on metric system Common units and quantities – Length – Volume – Mass – Temperature – Energy
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Conversions Move the decimal point to the left or right to convert within the metric system. – If you are going from a smaller unit to a larger unit move the decimal to the left. – If you are going from a larger unit to a smaller unit move the decimal to the right. kilohectodeca Base Unit (1) decicentimilli khdaMeter (m)dcm 100010010Gram (g)0.10.01.001 10 3 10 2 10 1 Liter (l)10 -1 10 -2 10 -3
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Convert the following measurements 245 m = _____________ cm 305 kg = _____________ g 35 mm = ______________ m 1250 cm = _____________ m 358 ml = ______________ l 2350 g = ______________kg 35 dm = ______________m 67 hm = ______________m
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In order to convert between different units of measurement you need to use conversion factors and the factor-label method. Example: A football field is 100. yds long. How long is that in m? 100. yards = 91.7 m 1.09 yd 1 m
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Example: A horse can gallop at a speed of 42.0 mph. How fast can the horse gallop in m/s? h 42.0 mi = 18.8 m/s 3600 s 1 h 1 mi 1609 m
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Convert the following English Standard Units to Metric Units. If I were to hit a home run down the left side of Jacobs Field the ball would have to travel at least 325 ft. How far is that in m? The top speed of a human is 10.4 m/s. How fast is that in mph?
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Convert the following English Standard Units to Metric Units. A race car can travel around 225 mph. How fast is that in m/s? A person can walk about 3.1 mph. How fast is that in m/s?
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Motion How can you tell an object is moving? – An object must change position with respect to a stationary background called a reference. What is relative motion?relative motion – It is movement in relation to a frame or reference.
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Distance vs. Displacement Distance is the length of the path between two points Displacement includes direction How is displacement different from Distance? What is the displacement of a roller coaster after one complete trip around the track?
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Speed What is the difference between average speed and instantaneous speed? – Average speed is the total distance divided by the total time – Instantaneous is the rate at a given moment
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Calculating Speed What units do you measure speed in? – We measure the speed of our cars and highway speed limits in miles/hour. – However in science class we measure speed using the SI units of meters/second. – Most other countries have highway speed limits posted in kilometers/hour, which is also a metric unit.
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Calculating Speed Speed or velocity = distance/time
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Example Problem A car traveled 350 miles toward New York City for 5 hours. What was the velocity of the car in mph and m/s?
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Example Problem A car traveled 35 miles/hour for 4 hours toward Chicago. How far did the car travel in miles and meters?
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Example Problem A plane travels 1925 miles toward Colorado at a velocity of 550 miles/hour. How much time has the plane been traveling in hours and seconds?
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Graphing Motion The slope on a distance-time graph is speed The slope on a velocity-time graph is acceleration
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Distance-Time Graph
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Speed vs. Velocity What’s the difference between speed and velocity? – The speed describes how fast an object is moving. – Velocity is a speed in a given direction.
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Acceleration What happens to you when you slam on the brakes in a car? What happens if you speed up very fast like on the top-thrill dragster at Cedar Point? Acceleration is defined as a change in velocity or direction divided by the time interval in which the change occurred.
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Calculating Acceleration
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Example Problem The Top Thrill Dragster at Cedar Point goes from 0 m/s to 53.6 m/s (120 mph) in 4 seconds. What is its acceleration?
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Example Problem A car traveling home at a velocity of 15.6 m/s slams on its brakes and comes to a stop to avoid a dog. If it takes 5 seconds to stop, what is the cars acceleration?
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Example Problem A Porsche Boxster has an acceleration of 4.51 m/s 2. If the car starts from rest how much time would it take for the vehicle to reach a speed of 11.3 m/s?
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Example Problem A bicyclist starts from rest and accelerates at 0.89 m/s 2 during a 5.0 s interval. What is the change in speed of the bicyclist and bicycle?
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Example Problem A golf ball thrown from the top of the sears tower accelerates at 9.8 m/s 2 toward the ground and lands on the pavement 9.2 seconds. If the ball’s final speed is 93.0 m/s what was the speed with which the ball was initial thrown?
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