Physical Science Chapter 11: Motion

Physical Science: Chapter 11, Motion Motion of objects is the change in their position

Frame of Reference Reference points are objects that stay in place. They are not in motion relative to the object in question. A frame of reference is used to describe the motion of an object relative to these reference points.

Physical Science: Chapter 11, Motion The motion of objects is the change in their position based on a frame of reference. Did the car move? How can you tell?

Physical Science: Chapter 11, Motion In physics, we usually use a “fixed” frame of reference

Physical Science: Chapter 11, Motion Distance measures how long the path is (total) that an object moves. (Distance =260 mi)

Physical Science: Chapter 11, Motion Displacement measures how far an object traveled from its starting point (net movement) (Displacement=188 mi)

Distance vs. Displacement

Physical Science: Chapter 11, Motion Displacement measures how far an object moved from its starting point.

Physical Science: Chapter 11, Motion If a person drove from the Civic Center 600m to Turman Dr, then west 1000m to Route 51, then 1600m to Church Rd, then 800m back to the Civic Center, a). What distance did they travel? b). What was their displacement?

Physical Science: Chapter 11, Motion a). What distance did they travel? Distance=600m +1000m +1600m +800m Distance =4000m b). What was their displacement? Displacement = 0 (They ended at the same point they started at).

Physical Science: Chapter 11, Motion Speed measures the distance traveled divided by the time in motion.

Physical Science: Chapter 11, Motion

Physical Science: Chapter 11, Motion You can find out your speed in a car by looking at the speedometer.

Physical Science: Chapter 11, Motion

Physical Science: Chapter 11, Motion

Physical Science: Chapter 11, Motion Velocity shows the speed AND the direction of movement. Is this ball moving up or down?

Physical Science: Chapter 11, Motion Velocity requires a frame of reference.

Physical Science: Chapter 11, Motion Velocity requires a frame of reference. ●The frame of reference can be “up” and “down”

Physical Science: Chapter 11, Motion Velocity requires a frame of reference. ● The frame of reference can be the x, y and z axis of a graph.

Physical Science: Chapter 11, Motion Velocity requires a frame of reference. ● The frame of reference can be the directions on a compass.

Physical Science: Chapter 11, Motion To find your velocity in a car you would need a speedometer and a compass to show direction

Physical Science: Chapter 11, Motion Velocities can be added together using “vectors.”

Physical Science: Chapter 11, Motion Velocity Vectors How would you find the velocity of someone walking on a moving sidewalk?

Physical Science: Chapter 11, Motion How would you find the velocity of an airplane flying with a cross wind blowing?

Physical Science: Chapter 11, Motion Mini-Quiz #1 1). What is the difference between distance and displacement? 2). What is the difference between speed and velocity? 3). What is the formula for average speed? 4). List THREE possible frames of reference for velocity?

Physical Science: Chapter 11, Motion Mini-Quiz #1 (Answers) 1). What is the difference between distance and displacement? Displacement has distance AND direction from a starting point. 2). What is the difference between speed and velocity? Velocity is speed AND direction from a starting point.

Physical Science: Chapter 11, Motion Mini-Quiz #1 (Answers) 3). What is the formula for average speed? Average speed = distance (moved) time (spent moving) 4). List THREE possible frames of reference for velocity? Up and down, x, y & z axis and points (directions) of a compass

Physical Science: Chapter 11, Motion

Physical Science: Chapter 11, Motion Average Speed Is not your “exact” speed. It is an average of your speeds for the entire distance you moved.

Physical Science: Chapter 11, Motion Average Speed In a triathlon, your average speed would be calculated 1.5km swim + 40km bike + 10km run total time swimming, biking & running

Physical Science: Chapter 11, Motion Instantaneous Speed Is your (theoretical) speed at a certain moment in your movement. It is impossible to measure exactly, but can be measured over very short time intervals.

Physical Science: Chapter 11, Motion Instantaneous Speed A speed gun cannot measure your speed at a one moment, but can estimate how fast you were going in a short time.

Physical Science: Chapter 11, Motion Average Velocity Average speed and average velocity are calculated the same way, but velocity includes the direction of movement.

Physical Science: Chapter 11, Motion Average Velocity Do Practice Problems (1 ,2) on page 369

Physical Science: Chapter 11, Motion Average Velocity (Answers) 1). Avg Speed = 110m 72.0s Velocity = 1.53 m/s to shore 2). Avg Speed = 38.0m 1.70s Velocity = 22.4 m/s to first base

Physical Science: Chapter 11, Motion Finding Distance & Time Avg Speed = distance time Distance = Avg Speed x time Time = distance Avg Speed

Physical Science: Chapter 11, Motion Finding Distance & Time 1). Practice Problem #3 on p. 369 2). How long would it take to travel the 340km to Jackson, MS at 100km/hr ? 3). How far is it to Jackson, TN if it took 2.0hr at 75km/hr?

Physical Science: Chapter 11, Motion Finding Distance & Time (Answers) 1). Distance = Avg Speed x time Distance = 12.0km/h x 5.0h Distance = 60.0km Displacement = 60km southwest

Physical Science: Chapter 11, Motion Finding Distance & Time 2). How long would it take to travel the 340km to Jackson, MS at 100km/h? Time = distance = 340km Avg Speed 100km/h Time = 3.4h

Physical Science: Chapter 11, Motion Finding Distance & Time 3). How far is it to Jackson, TN if it took 2.0hr at 75km/hr? Distance = Avg Speed x time Distance = 75km/h x 2.0h =150km

Physical Science: Chapter 11, Motion Mini-Quiz #2 1). What is the difference between average and instantaneous speed? 2). What is the average speed for a sprinter who runs 100.0m in 12s? 3). How long does it take a person walking at 5km/h to walk 35km? 4). How far will a car travel in 4h at 12km/h ?

Physical Science: Chapter 11, Motion Mini-Quiz #2 (Answers) 1). What is the difference between average and instantaneous speed? Average speed is the total distance divided by the total time (average of all the speeds); instantaneous speed is the speed at ONE INSTANT in time.

Physical Science: Chapter 11, Motion Mini-Quiz #2 (Answers) 2). What is the average speed for a sprinter who runs 100.0m in 12s? Speed = distance = 100.0m = 8.3 m/s time 12s 3). How long does it take a person walking at 5km/h to walk 35km? Time = distance = 35km = 7h speed 5km/h

Physical Science: Chapter 11, Motion Mini-Quiz #2 (Answers) 4). How far will a car travel in 4h at 12km/h? Distance = Speed x Time = Distance = 12km/h x 4h = 48km