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Metric Prefixes Practice 1.If a radio wave has a period of 1 µs, what is the period in seconds? 2.A hydrogen atom has a diameter of about 10 nm. – Express this diameter in meters. – Express this diameter in millimeters. – Express this diameter in micrometers. 3.The distance between the sun and Earth is about 1.5 X m. Express this distance in kilometers and gigameters.

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Frame of Reference A system that defines where objects are for a problem. For certain problems, there may be multiple frames of reference that can be used.

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Scalar Vs. Vector Scalar Vector

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Displacement Similar to distance, but displacement will also include the direction traveled. Direction is indicated by a positive or negative number. Positive means right or up and negative means left or down. Equation: Δx=x f -x i Units:

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Velocity

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Average Velocity Example During a race on level ground, Andra runs with an average velocity of 6.02 m/s east, what is her displacement after 137 s?

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Average Velocity Problems 1.Heather and Matthew walk with an average velocity of 0.98 m/s east. If it takes them 34 minutes to walk to the store, what is their displacement? 2.If Joe rides his bicycle in a straight line for 15 minutes with an average velocity of 12.5 km/hr south, how far has he ridden?

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Problems Continued 3.Simpson drives his car with an average velocity of 48.0 km/hr east. How long will it take him to drive 144 km on a straight road? 4.A bus travels 280 km south along a straight path with an average velocity of 88 km/hr south. The bus stops for 24 minutes. Then, it travels 210 km south with an average velocity of 75 km/hr south. How long does the total trip last? What is the overall average velocity?

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Instantaneous Velocity Instantaneous velocity can be found on a position vs. time graph. It is the velocity at a given point in time. It is found by finding the slope of the tangent line at that point of the graph. Tangent line-

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What is the instantaneous velocity at 1s, 3s, 4.2s and 7.3s?

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Acceleration

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Velocity and Acceleration vivi amotion ++ speeding up slowing down -+ + or -0 constant velocity 0+ or - speeding up from rest 00 at rest

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Average Acceleration Example A shuttle bus slows down with an average acceleration of -1.8 m/s 2. How long does it take the bus to slow from 9.0 m/s to a complete stop?

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Average Acceleration Problems 1.A car traveling at 7.0 m/s accelerates uniformly at 2.5 m/s 2 to reach a speed of 12.0 m/s. How long does this take? 2.With an average acceleration of -1.2 m/s 2, how long will it take to bring a bicycle at a speed of 6.5 m/s to a complete stop?

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Problems Continued 3.Turner’s treadmill runs with a velocity of -1.2 m/s and speeds up at regular intervals during a half-hour workout. After 25 min, the velocity is -6.5 m/s. What is the average acceleration during this period? 4.Suppose a treadmill has an average acceleration of 4.7X10 -3 m/s 2. How much will the speed change after five minutes? If the initial speed is 1.7m/s, what is the final speed?

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Displacement With Constant Acceleration

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Example A racing car reaches a speed of 42 m/s. It undergoes a constant acceleration and comes to a rest 5.5 s later. How far did the car take to stop?

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Problems 1.A car accelerates uniformly from rest to a speed of 6.6 m/s in 6.5 s. Find the distance. 2.A driver in a car traveling at a speed of 21.8 m/s sees a cat 101 m away on the road. How long will it take for the car to accelerate uniformly to rest in 99 m. 3.A car enters the freeway with a speed of 6.4 m/s and accelerates for 3.2 km in 3.5 min. How fast is the car moving at the end?

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Velocity and Displacement With Constant Acceleration

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Example A plane at rest accelerates at 4.8 m/s 2 for 15 seconds and takes off. What is the speed at takeoff? How long must the runway be?

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Problems 1.A car with an initial speed of 6.5 m/s accelerates at a uniform rate of 0.92 m/s 2 for 3.6 s. Find the final speed and displacement. 2.An automobile with an initial speed of 4.3 m/s accelerates at 3.0 m/s 2. Find the final speed and displacement after 5.0 seconds.

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Problems Continued 3.A car starts from rest and travels for 5.0 s with an acceleration of -1.5 m/s 2. What is the final velocity? How far does it travel? 4.A car traveling at 15 m/s applies the brakes and accelerates at -2.0 m/s 2. How long does it take to accelerate to 10 m/s? How far did the car travel?

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Final Velocity After Any Displacement

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Example A person pushing a stroller starts from rest and accelerates at 0.5 m/s 2. What is the velocity after 4.75 m?

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Problems 1.A car traveling at 7.0 m/s accelerates at 0.8 m/s 2 for 245 m. What is the final velocity? What is the velocity after 125 m? 2.A car accelerates from rest at a rate of 2.3 m/s 2. What is the speed after 55 m? How long does it take to travel 55 m?

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Problems Continued 3.An aircraft has a liftoff speed of 33 m/s. What minimum acceleration does this require if the plane lifts off after 240 m? 4.A certain car is capable of accelerating at 0.85 m/s 2. What is the magnitude of the car’s displacement as it accelerates from 83 km/hr to 94 km/hr?

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Mixed Problems 1.Nathan accelerates his skateboard from rest to 12.5 m/s in 2.5 s. a)What is his acceleration? b)What is his displacement? c)What is his average velocity? 2.Marissa’s car accelerates at a rate of 2.6 m/s 2 how long does it take to go from 24.6 m/s to 26.8 m/s?

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Free Fall An object in free fall is falling toward the Earth and the only force acting on it is gravity. Every object experiences the same acceleration due to gravity. g= Also, since the acceleration is downward, g will be negative. The acceleration is the same for an object going straight up.

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Free Fall Example Jason hits a volleyball with an initial velocity of 6.0 m/s upward. If the ball starts 2 m above the floor, how long will it be in the air?

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Assignment Page a) -42 m/s b) 11 s 2.a) 22.1 m/sb) 2.25 s 3.a) 8.0 m/sb) 1.63 s m

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