Motion :Motion Speed, acceleration, momentum


Frames of Reference :Frames of Reference Object or point from which motion is determined Most common is the Earth Motion is a change in position relative to a frame of reference


What is motion? :What is motion? If you are standing in one place, and your friend walks by you, are you moving relative to your friend? Is your friend moving relative to you? Is either of you moving relative to the earth?


Answer: :Answer: You are moving relative to your friend, and your friend is moving relative to you! You are not moving relative to the earth, but your friend is. You are both moving relative to the sun!


What is motion? :What is motion? If you and your friend are walking down the hall together at the same speed, in the same direction, are you moving relative to your friend? Is your friend moving relative to you? Are either of you moving relative to the Earth?


Answer: :Answer: You are NOT moving relative to your friend, and your friend is NOT moving relative to you. You both are moving relative to the earth.


Speed :Speed Speed = Distance ÷ Time D_ S T Example: A car travels 300km in 6 hours. What is the speed of the car?


Answer: :Answer: Speed = distance ÷ time Speed = 300km ÷ 6 hours Speed = 50km/hr


More practice :More practice 1. How far can a plane travel if it flies 800km/hr for 9 hours? 2. How long does it take a ship to go 500 km if it travels at a speed of 50km/hr?


Answer :Answer 1. D S T D 800 9 800km ▪ 9hrs = 7200km hr


Answer :Answer 2. D S T 500 50 T 500km ÷ 50km = 10 hrs hr


Velocity :Velocity Speed in a given direction. What is the velocity of a boat that travels from St. Peter to Mankato (10 miles) in 15 minutes?


Answer :Answer Speed = distance ÷ time Speed = 10 miles ÷ 15 minutes Speed = 0.67 mi/min Velocity = 0.67 mi/min South


Change your answer to mi/hr! :Change your answer to mi/hr! 0.67mi/min x 60min/hr = 40 mi/hr


Distance-time graphs :Distance-time graphs On your paper, graph the following: D (m) T (sec) 0 0 5 7 10 14 15 21


Slide 16:time (sec) Distance (m)


Was your graph a straight line? :Was your graph a straight line? A distance-time graph which is a straight line indicates constant speed. In constant speed, the object does not speed up or slow down. The acceleration is zero.


Graph the following on a distance-time graph: :Graph the following on a distance-time graph: D (m) T (s) 0 0 5 1 20 2 45 3 80 4 125 5


Slide 19:time (sec) Distance (m) 0 1 2 3 4 5


Was your graph a curve? :Was your graph a curve? A graph that curves on a distance-time graph shows that the object is accelerating


Distance-time graphs :Distance-time graphs Describe the motion of the object as shown in the graph. From 0-8 sec, constant speed: (25 m/sec); From 8-12 sec, no motion; From 12-16 sec, acceleration; From 16-20 sec, constant speed


Speed-time graphs :Speed-time graphs Using the distance-time graph from the last frame, draw a speed time graph. First fill in the table below: Average Speed (m/s) Time (sec) ____ 0 to 8 ____ 8 to 12 ____ 12 to 20 25 0 37.5


What does your graph look like? :What does your graph look like? Constant speed will be a horizontal line on a speed time graph. If the speed decreases, the line will slant down. If the speed increases, the line will slant up.


What do the following speed-time graphs depict? :What do the following speed-time graphs depict?