Motion

Where does the car have the most potential energy? a) Between A and B b) Between B and C c) Between C and D d) After D

Where does the car have more kinetic energy than potential? a) A b) B c) C d) D

Describing Motion 1) Speed = rate at which an object moves (“how fast”) moves (“how fast”)

Describing Motion 1) Speed = rate at which an object moves (“how fast”) (“how fast”) speed equation: speed = distance ÷ time (v = d ÷ t) (v = d ÷ t) distance = “how far” object traveled time = “how long” object traveled units of speed: meters per second (m/s) or kilometers per hour (km/hr)

A jogger runs the first 1000 m of a race in 250 sec. What is the jogger’s speed? What is the correct way to plug in the numbers? a) v = 250 sec ÷ 1000 m b) v = 1000 m ÷ 250 sec c) v = 1000 m x 250 sec d) v = 250 sec x 1000 m

Describing Motion 1) Speed = rate at which an object moves speed = distance ÷ time (v = d ÷ t) A jogger runs the first 1000 m of a race in 250 sec. What is the jogger’s speed? v = 1000 m ÷ 250 sec v = 1000 m ÷ 250 sec

A jogger runs the first 1000 m of a race in 250 sec. What is the jogger’s speed? a) v = 0.25 m/sec b) v = 0.25 sec/m c) v = 4 m/sec d) v = 4 sec/m

Describing Motion 1) Speed = rate at which an object moves speed = distance ÷ time (v = d ÷ t) A jogger runs the first 1000 m of a race in 250 sec. What is the jogger’s speed? v = 1000 m ÷ 250 sec v = 4 m/sec

Distance-Time Graphs Distance-Time Distance-Time Graphs = used to represent a person or object’s motion

How long had both boys been running before they met? a) 4 sec b) 2.7 sec c) 27 yards d) 20 yards

How far did the red boy run before he met the blue boy? a) 40 yards b) 27 yards c) 2.7 sec d) 20 yards

What was the blue boy’s speed? a) 20 yards b) 5 yds/sec c) 20 yds/sec d) 10 yds/sec

Describing Motion 1) Speed = rate at which an object moves 2) Velocity = speed with a specific direction

A running back moves towards the east end zone at 10 m/sec. What is the running back’s velocity? a) 10 m/sec b) 10 m/sec west c) 10 m/sec east d) 10 meters east

Describing Motion 1) Speed = rate at which an object moves 2) Velocity = speed with a specific direction 3)Acceleration = change in velocity over time

Describing Motion 3) Acceleration = change in velocity over time –Acceleration can mean: Speeding up = positive (+) acceleration Speeding up = positive (+) acceleration

Describing Motion 3) Acceleration = change in velocity –Acceleration can mean: Speeding up = positive (+) acceleration Speeding up = positive (+) acceleration Slowing down = negative (-) acceleration Slowing down = negative (-) acceleration

Describing Motion 3) Acceleration = change in velocity –Acceleration can mean: Speeding up = positive (+) acceleration Speeding up = positive (+) acceleration Slowing down = negative (-) acceleration Slowing down = negative (-) acceleration Changing direction Changing direction –Think of a rollercoaster because it can do all three!

Which car is not accelerating? a) A car driving up a hill and down the other side. b) A car turning a corner. c) A car turning a corner at a constant speed. d) A car driving at a constant speed along a straight highway.

Which is NOT an example of acceleration? a) As you see your friend, you jump up and run to greet them. b) Your dog runs in circles chasing his tail. c) You pedal your bike along your street at 5 km/hr. d) A car slows down as it comes to a red light.

Describing Motion 3) Acceleration = change in velocity over time acceleration equation: acceleration = velocity ÷ time (a = v ÷ t) units of acceleration: m/s per second (m/s 2 ) or km/hr per hour (km/hr 2 )

You’re running late, so you accelerate from 0 to 72 km/hr in 8 sec. What is your acceleration? What is the correct way to plug in the numbers? a) a = 72 km ÷ 8 sec b) a = 0 km/hr ÷ 8 sec c) a = 72 km/hr ÷ 8 sec d) a = 8 sec ÷ 72 km/hr

3) Acceleration = change in velocity acceleration = velocity ÷ time (a = v ÷ t) You’re running late, so you accelerate from 0 to 72 km/hr in 8 sec. What is your acceleration? a = 72 km/hr ÷ 8 sec. Describing Motion

You’re running late, so you accelerate from 0 to 72 km/hr in 8 sec. What is your acceleration? a) 9 km/hr b) 9 km/hr/sec c) 9 km/hr/hr d) 9 km

Acceleration = change in velocity Acceleration = change in velocity acceleration = velocity ÷ time (a = v ÷ t) A car accelerates from 0 to 72 km/hr in 8 sec. What is the car’s acceleration? a = 72 km/hr ÷ 8 sec. a = 9 km/hr/s Describing Motion

You see a police car and slow down from 72 km/hr to 62 km/hr in 2 sec. What is your acceleration? What is the correct way to plug in the numbers? a) a = 72 km ÷ 2 sec b) a = 10 km/hr ÷ 2 sec c) a = -10 km/hr ÷ 2 sec d) a = 62 km/hr ÷ 2 sec

3) Acceleration = change in velocity acceleration = velocity ÷ time (a = v ÷ t) You see a police car and slow down from 72 km/hr to 62 km/hr in 2 sec. What is your acceleration? a = -10 km/hr ÷ 2 sec. Describing Motion

You see a police car and slow down from 72 km/hr to 62 km/hr in 2 sec. What is your acceleration? a) -5 km/hr b) -5 km/hr/sec c) 5 km/hr/sec d) 0.5 km/hr/sec

Acceleration = change in velocity Acceleration = change in velocity acceleration = velocity ÷ time (a = v ÷ t) You see a police car and slow down from 72 km/hr to 62 km/hr in 2 sec. What is your acceleration? a = -10 km/hr ÷ 2 sec. a = -5 km/hr/s Describing Motion