Motion Notes Ms. Rudisill

Motion An object is in motion if it is changing position. Depends on two “points of reference” – a starting position and an ending position.

Distance The movement of an object from one point of reference to another.

Displacement The distance between the starting and ending points and the direction you have traveled.

Speed Distance Speed = Time

Practice Problem #1 Distance Distance = 100 m Speed = Time Calculate the speed of a swimmer who swims 100 meters in 56 seconds. Distance Distance = 100 m Speed = Time Time = 56 sec 100 meters Speed = = 1.79 m/sec 56 seconds

Practice Problem #2 Distance Distance = 350 km Speed = Time A passenger train travels from Boston to New York, a distance of 350 km, in 3.5 hours. What is the train’s speed? Distance Distance = 350 km Speed = Time Time = 3.5 hours 350 km Speed = = 100 km/hrs 3.5 hours

Velocity The speed of an object AND the direction of its motion.

Practice Problem #3 Distance Distance = 5 m (to the left) Velocity = Calculate the average velocity of a dancer who moves 5 m toward the left of the stage over the course of 15 sec. Distance Distance = 5 m (to the left) Velocity = Time Time = 15 sec 5 m = 0.33 m/sec to the left Velocity = 15 sec

Acceleration Change in velocity divided by the amount of time it takes for the change to occur.

Acceleration Equation (Final Speed) - (Starting Speed) Acceleration = Time

Three Kinds of Acceleration: Speeding up Slowing down Changing direction

(Final Speed) - (Starting Speed) Practice Problem #4: Calculate the acceleration of a bus whose speed changes from 6 m/sec to 12 m/sec over a period of 3 sec. (Final Speed) - (Starting Speed) Acceleration = Time Final Speed = 12 m/sec. Starting Speed = 6 m/sec. Time = 3 sec.

Practice Problem #4: (12 m/s) - (6 m/s) Acceleration = 3 s Acceleration = 2 m/s2

(Final Speed) - (Starting Speed) Practice Problem #5: Calculate the acceleration of a train whose speed increases from 7 m/s to 17 m/s in 120 s. (Final Speed) - (Starting Speed) Acceleration = Time Final Speed = 17 m/s Starting Speed = 7 m/s Time = 120 s

Practice Problem #5: (17 m/s) – (7 m/s) Acceleration = 120 s Acceleration = 0.083 m/s2