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Calculating Speed, Velocity, Acceleration, and Kinetic Energy. Formulas to remember. Speed = Distance / time Average Speed = Total distance / total time Velocity = Distance / time + direction Acceleration= Final Velocity – Initial Velocity time
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Calculating Speed, Velocity, Acceleration, and Kinetic Energy
Formulas to remember • Speed = Distance / time • Average Speed = Total distance / total time • Velocity = Distance / time + direction • Acceleration= Final Velocity – Initial Velocity • time • Kinetic Energy= ½ mass x speed2
Units to remember • Distance: mm,cm,m,km, mile • Time: s, min, h • Speed: m/s, km/h, mi/h • Velocity: m/s, km/ h, mi/h + directional word • (directional words – north, south, east, west, up, down, toward, away from, left, right) • Acceleration: mi/h/s, m/s/s or m/s2, km/h/s + Direction • Energy: J or joules
Problem 1 The fastest speed achieved by a snail in the Guinness Gastropod Championship, was achieved over a 33 m course in central London, and is held by a mollusk called Archie. It took Archie 140 seconds to cover the 33 m course. What was Archie's speed in m/s?
Speed = distance / time • 33m / 140 s = 0.2357 m/s • (round off to 0.24 m/s)
A driver, not anticipating an accident, can apply the brakes fully in about 0.5 seconds. How far would a car driving down the freeway at 30 m/s travel in this time? S=d/t d = t x S t = d / S
distance = time x Speed D = .5 s x 30 m/s Distance = 15 meters
Ms. Barsegyan is driving at a speed of 105km/hr on the 2 North freeway to go to Mrs. Lalaian’s house. What is her speed? What is her velocity?
Speed = 105km/hrVelocity = 105km/hr NorthboundVelocity is a Vector and Speed is NOT
Mrs. Cervantes runs 30 METERS in 5 seconds to 1st base. She waits for 60 seconds for the next batter, who hits a homerun. Mrs. Cervantes ruNs the remaining 70m to the 2nd base, 3rd base and home in 10 SECONDS. WHAT IS HER AVERAGE SPEED BACK TO THE BATTER BOX?
A roller coaster is moving at 25 m/s at the bottom of a hill. Three seconds later it reaches the top of the hill, moving at 10 m/s. What is the acceleration of the roller coaster?
10 m/s – 25 m/s = -15 m/s = - 5 m/s2 3 s 3 s up hill Deceleration or negative acceleration
A driver starts his parked car and within 5 seconds reaches a velocity of 55 km/h as he travels east. What is his acceleration?
Good Job, Man! 55 km/h – 0 km/h = 55 km/h = 11 km/h/s 5 sec 5 s east
Remember: a change in velocity (speed/direction or both) is acceleration A = final velocity – initial velocity time to change velocity SI unit for acceleration is m/s/s or m/s 2
Calculate the kinetic Energy of a 200kg ball with a speed of 2m/sRemember KE=1/2 mass*speed2