2Velocity rate of change of displacement. a speed in a given direction or velocity a vector quantity direction magnitude (speed) Velocity is...
speed = 300 km/h direction = west Train engineers use speed only. aSpeed with direction 2Velocity Pilots use velocity (direction & speed). speed = 90 km/h
bAverage velocity Average velocity = overall displacement total time of travel direction of velocity = direction of overall displacement 2Velocity
Question 3 A student runs around a circular track that is 1000m in length in a time of 30 min. What is the average velocity of the student? 0 m/min If the student runs completely around the track, they are back where they began. So their overall displacement is zero.
cInstantaneous velocity The velocity at any instant is called instantaneous velocity. If a car moves at a constant velocity... … its average and instantaneous velocities have the same value. 2Velocity
Question 4 Which of these is a correct velocity? A.55 miles per hour B.15 kilometers per second C.30 meters per second east D.400,000,000 meters per hour
3Acceleration When an object moves faster and faster, its speed is increasing (velocity changed).
3Acceleration When an object moves slower and slower, its speed is decreasing (velocity changed).
When an object changes direction, 3Acceleration its velocity changes too.
3Acceleration Acceleration measures the change in velocity Acceleration = velocity per unit time direction speed overall change in velocity total time taken = m/s 2 Unit: m/s/s vector quantity =
If a car accelerates at 2 m s –2, what does that mean? 3Acceleration t = 1 s v = 2 m s –1, v = 2 m s –1 v = 0 t = 2 s v = 4 m s –1, v = 2 m s –1 v = 6 m s –1, v = 2 m s –1 t = 3 s 1 m t = 0 3 m 5 m
Tommy accelerates from 20 m/s at 15 sec (t 1 ) to 40 m/s at 60 sec (t 2 ). Question 5 What is his avg. acceleration between t 1 and t 2 ? Avg. acceleration = 40 m/s – 20 m/s 60s – 15 s 20 m/s 45 s = =.44 m/s 2