Motion Speed, acceleration, momentum

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

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

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

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? 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 Is your friend moving relative to you? Are either of you moving Are either of you moving relative to the Earth?

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

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

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

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

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

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

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

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

Distance-time graphs On your paper, graph the following: On your paper, graph the following: D (m) T (sec) D (m) T (sec)

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

Graph the following on a distance- time graph: D (m)T (s) D (m)T (s)

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

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

Speed-time graphs Using the distance-time graph from the last frame, draw a speed time graph. First fill in the table below: 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

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

What do the following speed-time graphs depict?