Physical Science Chapter 11: Motion.

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.

The motion of objects is the change in their position based on a frame of reference. Did the car move? How can you tell?

In physics, we usually use a “fixed” frame of reference

Distance measures how long the path is (total) that an object moves. (Distance =260 mi)

Displacement measures how far an object traveled from its starting point (net movement) (Displacement=188 mi)

Distance vs. Displacement

Displacement measures how far an object moved from its starting point.

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?

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).

Speed measures the distance traveled divided by the time in motion.

You can find out your speed in a car by looking at the speedometer.

Velocity shows the speed AND the direction of movement. Is this ball moving up or down?

Velocity requires a frame of reference.

Velocity requires a frame of reference. ●The frame of reference can be “up” and “down”

Velocity requires a frame of reference. ● The frame of reference can be the x, y and z axis of a graph.

Velocity requires a frame of reference. ● The frame of reference can be the directions on a compass.

To find your velocity in a car you would need a speedometer and a compass to show direction

Velocities can be added together using “vectors.”

Velocity Vectors How would you find the velocity of someone walking on a moving sidewalk?

How would you find the velocity of an airplane flying with a cross wind blowing?

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?

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.

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

Average Speed Is not your “exact” speed. It is an average of your speeds for the entire distance you moved.

Average Speed In a triathlon, your average speed would be calculated 1.5km swim km bike km run total time swimming, biking & running

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.

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.

Average Velocity Average speed and average velocity are calculated the same way, but velocity includes the direction of movement.

Average Velocity Do Practice Problems (1 ,2) on page 369

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

Finding Distance & Time Avg Speed = distance time Distance = Avg Speed x time Time = distance Avg Speed

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?

Finding Distance & Time (Answers) 1). Distance = Avg Speed x time Distance = 12.0km/h x 5.0h Distance = 60.0km Displacement = 60km southwest

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

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

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 ?

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.

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 s 3). How long does it take a person walking at 5km/h to walk 35km? Time = distance = 35km = 7h speed km/h

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

Physical Science Chapter 11: Motion.

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Physical Science Chapter 11: Motion.

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