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motion. How can we tell if an object has moved??. Motion : when an object changes its position relative to a reference point Frame of Reference: a coordinate system in which the position of the objects is measured
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Motion: when an object changes its position relative to a reference point Frame of Reference: a coordinate system in which the position of the objects is measured ReferencePoint: where the x-axis and the y-axis of the frame of reference intersect Motion and Position
Distance: how far an object has moved Displacement: the distance and direction of an object’s change in position from the starting point Distance vs. displacement
Can the displacement of an object every be more than the distance an object traveled? Distance vs. displacement
A squirrel runs 4.8 m across a lawn, stops and runs 2.3 m back in the opposite direction. What is the squirrels displacement from its starting point? Displacement = 4.8 m – 2.3 m = 2.5 m Calculating displacement
A cyclist leaves home and rides due east for a distance of 45 km. She returns home on the same bike path. What is her displacement? Displacement = 45 km – 45 km = 0 km Calculating displacement
Speed: the distance an object travels per unit time Speed (s) = distance (d) / time (t) speed
Speed metres Speed = distance traveled time taken Metres per second (m/s) seconds
Speed kilometres Speed = distance traveled time taken Kilometres per hour (km/h) hours
A car traveling at a constant speed covers a distance of 750 m in 25 s. What is the car’s speed? Distance = 750 m Time = 25 s s = d/t 750/25 = 30 m/s Practice calculating speed
What if we know the speed of an object and the time it moved for and need to calculate the distance traveled? speed = distance/time Distance = speed x time Distance traveled
Mrs. Cowley’s drive to work takes her 30 minutes. If she drives at an average speed of 80 km/h, what is the distance between the school and her house? d = s x t d = 80 km/h x .5 h d = 40 km calculating distance traveled
ConstantSpeed: no acceleration or deceleration occurs AverageSpeed: the speed of motion when speed is changing over time Instantaneousspeed: the speed at a given point in time Motion with constant speed
What are 2 examples of motion in which the instantaneous speed changes? Learning check
Distance-timegraph: shows the motion of an object over a period of time Time is plotted on the x-axis Distance is plotted on the y-axis Graphing motion
Straightline: the object moves with a constant speed Steeperslope = faster movement Horizontalline = object is at rest Graphing motion
Curvedlines: to the right = getting slower, to the left = getting faster Graphing motion
Velocity: includes the speed AND direction of an object Velocity
Acceleration: the rate of change of an objects velocity Acceleration occurs when an object changes speed, direction or both Acceleration
a = Vƒ - Vί t a = acceleration Vί = initial velocity Vƒ = final velocity t = time Acceleration Equation
A plane stars at rest on a runway. After 20 seconds the speed of the plane is 80 m/s. Calculate the acceleration of the plane. a = Vƒ– Vί t a = 80 m/s – 0 m/s 20 s a = 4 m/s Practice Problem
A skateboarder is slowing down to a stop. He is moving at a speed of 3 m/s. He comes to a stop in 2 seconds. Calculate the skaters acceleration. a = Vƒ – Vί t a = 0 m/s – 3 m/s 2 s a = -1.5 m/s Practice Problem