Choosing a Frame of Reference

From which frame of reference would the tree be moving?

If you were sitting under the tree which objects would appear to be in motion?
To describe motion accurately and correctly, a _______________________________ is needed
Could a passenger in a moving car appear to be at rest? _____________________________________________
Relative motion is movement in relation to _____________________________________________
Measuring Distance
Distance is the ___________________ of the path between two points.
If the object moves in a straight line, the distance is the length of the line from __________________________
You also have to choose the correct _________________ for distance
Which SI unit of distance would you use to measure: (m, km, or cm?) a) the distance the airplane travels _____ b) the height of the tree _____c) the length or width of a leaf _____
Measuring Displacement
Displacement describes an object’s position or location relative to the starting point called the ____________
Displacement is not the same as distance! I could go 100 miles but have a displacement equal to zero!
Combining Displacements
Displacement is called a vector quantity because it includes _________________________________________
Vectors can be represented by arrows where the length of the arrow represents the ____________________
Adding vectors is called vector addition, and the sum of vectors is called the ____________________________
Vector Addition
When vectors have the same direction, you ________________ their magnitudes
When vectors have opposite directions, you can _________________ their magnitude
Sometimes you add vectors with completely different directions graphically using a ruler

11.1 EXAMPLES AND PRACTICE:
Example 1: A car drives 5 miles east, then 2 more miles east
What is the distance? _______________________________
What is the displacement? _______________________________
Example 2: A car drives 5 miles east, then 2 miles west
What is the distance? _______________________________
What is the displacement? _______________________________
Example 3: A group of hikers start off at their campsite and travel 4 km east, turn north for 5 km, and finally back west for another 2 km. How far are the hikers from their original campsite?
(HINT: Use a ruler and have 1 cm = 1km, then measure the displacement from the beginning to the end)
1) A man drives 6 blocks N, 5 blocks E, and then 6 blocks south. How could the driver have made the distance shorter while maintaining the same displacement?
2) Two cars start at the same point and drive in a straight line for 5 km. At the end of the drive their distances are the same but their displacements are different. Explain how this can be true:
3) Write a word problem below that describes an object with a distance equal to 10 km, but a displacement that is equal to zero. Draw a diagram that illustrates the problem:
4) A whale swims east for 6.9 km, turns around and goes west for 1.8 km, and turns around again and heads 3.7 km east. Draw the diagram and find the distance and displacement for the journey.
Total distance: ________________
Displacement: ________________
5) A spider crawls along a wall. He climbs 1 m up the wall, then 2 m left, then 1 m down. Draw the diagram and find the distance and displacement for the journey.
Total distance: ________________
Displacement: ________________

11.1 Questions
1. What do you need in order to describe motion accurately and completely?
2. What is a frame of reference and how is it used to measure motion?
3. Movement in relation to a frame of reference is called _________________________.
4. You are travelling as a passenger in a car. Circle the letter of the best frame of reference you could use to determine how fast the car is moving relative to the ground:
A. people sitting next to you
C. a van traveling in the next lane
B. the driver of the car
D. a sign post on the side of the road
5. Which unit of length would you use to measure the following?
A. The Tchefuncte River _________________
B. The length and width of your living room _________________
C. the length of a pencil _________________
6. T or F? Five blocks south is an example of a displacement
7. How are distance and displacement similar? How are they different?
8. A ball rolls uphill 5 meters then back downhill for 7 meters. What is the ball’s displacement?
9. What would your total displacement be if you walked around the block? _________________
10. A vector is a quantity that has both _____________________ and ________________________.
11. The magnitude of a vector is another word for the vector’s ______________________.
12. How do you combine two displacement vectors: a) that are in the same direction? __________________________ b) that are in opposite directions? __________________________ c) that are in completely different directions? ______________________
13. Refer to the vector diagram:
7 km
3 km
A. What are the magnitudes of the displacement vectors? __________________
B. What is the total displacement? ___________________________
14. What is the displacement of a cyclist who travels 1 mile north, 1 mile east, and then 1 mile south?
15. The vector sum of 2 or more vectors is called the _____________________________________.

Speed is the ratio of the __________________ an object moves to the _______________ it takes
The SI unit of speed is _______________________ but in some cases you will use km/hour
There are two ways to express the speed of an object:
Instantaneous speed: ____________________________________________________
Average speed: _________________________________________________________
Calculating Average Speed : 𝑎𝑣𝑒𝑟𝑎𝑔𝑒 𝑠𝑝𝑒𝑒𝑑 = 𝑡𝑜𝑡𝑎𝑙 𝑑𝑖𝑠𝑡𝑎𝑛𝑐𝑒 𝑡𝑜𝑡𝑎𝑙 𝑡𝑖𝑚𝑒
, 𝑜𝑟 𝑣̅ = 𝑑 𝑡
Example: While travelling on vacation, you travel 35 kilometers in 0.4 hours, then 53 kilometers in 0.6 hours. What is your average speed? (Hint: Find the total distance and total time first)
Average speed is helpful to determine how long a particular trip will take, but instantaneous speed is what is shown on your car’s speedometer
Graphing Motion:
A distance-time graph is a good way to describe motion
Examples:

The slope on a distance time graph will equal the ____________________ (steeper slope= faster)

A positive slope indicates movement _________________________ the origin

A negative slope indicates that the object is moving _______________________ the origin

A straight line on a distance time graph indicates a ________________________

A curved line on a distance-time indicates ________________________

A flat line indicates that the object is ____________________________
Velocity:
Velocity is a vector quantity that describes the ___________________________
You can vectors arrows to represent velocity (just like displacement) - a longer arrow indicates _____________
A change in velocity could mean a change in ___________________ or a change in _____________________
*An object going around a curve at a constant speed has a changing velocity

11.2 PRACTICE:
1. Do the cyclists start at the same point? If not, which one starts ahead?
2. Which cyclist is faster?
3. At t = 7s, which cyclist is ahead in the race?
4. What happens at the point where the lines intersect?
Describe the motion of the object for the given time interval:
5. Between 0 and 3 sec:
6. Between 3 and 5 sec:
7. Between 5 and 8 sec:
8. Describe how it is possible that the speed could be equal for the first and last parts of the trip, but not the velocity:
This distance time graph shows Marie’s Trip to Work:
9. At which point does Marie realize she forgot her briefcase and head back home?
10. At some point, Marie has to wait for a train to pass. How long does she wait?
11. During what interval does she travel slowest? Fastest?
12. A boat travels downstream with a velocity of 11 km/hr relative to the river. If the current of the river is 5 km/hr, what is the total velocity of the boat relative to the riverbank?
11 km/hr
5 km/hr
13. A boat attempts to travel directly across a river at a velocity of 12 km/hr, but the current pushes it downstream at a velocity of 5 km/hr. What is the resultant velocity? (HINT: Use Pythagorean Theorem)
5 km/hr

11.2 Questions:
1. Define speed:
2. The SI units for speed are:
3. How is instantaneous speed different from average speed?
4. The equation used to calculate average speed is:
5. T or F? You can calculate how fast you were travelling at the midpoint of your trip by calculating your average speed for the entire trip.
6. A student walked 1.5 km in 25 minutes, then realizing he was late, ran the last 0.5 km in 5 minutes. What was his average speed (in km/hr?)
7. What type of speed does an automobile’s speedometer display?
8. What shows the speed on a distance-time graph?
9. Create a distance time graph based on the following info, and then answer the questions:

Draw a point on the graph that represents Train A traveling 200 km in 4 hours. Draw a line connecting this point to the origin and label it A

Draw another point on the graph representing Train B traveling 100 km in 10 hours. Draw a line connecting this point to the origin and label it B a) Which line shows the fastest speed? How can you tell? b) How would you calculate the average speed of train A? c) How much faster was train A traveling than train B?
10. What is the difference between speed and velocity?
11. How is it possible to have a constant speed but a changing velocity?
12. An Olympic swimmer swims 50.0 meters in 23.1 seconds. What was his average speed?
13. A plane’s average speed is 600 km/hr. If the trip takes 2.5 hours, how far does the plane fly?

Chapter 11.3: Acceleration
Acceleration is the rate at which ______________________________ changes
Acceleration can be a change in ______________________ or _______________________
A horse on a carousel that is going a constant speed is still accelerating. Why?
Acceleration also has magnitude and direction, making it a __________________________ quantity
An object in free fall is accelerated by ________________________
The acceleration due to gravity is _______, which means gravity increases your speed that much each second
Example problem: Ignoring air resistance, how fast is an object in free fall travelling after 3 seconds?
Constant acceleration is a steady change in ______________________________
If velocity is constant, acceleration will be equal to _______________________
If the final velocity is greater than the initial velocity, the acceleration will be __________________
If the final velocity is less than the initial velocity, the acceleration will be ___________________
Example problem: A skateboarder begins down a ramp at a speed of 1.0 m/s. After 3 seconds, her speed has increased to 4.0 m/s. Calculate her acceleration:
VELOCITY-TIME GRAPHS: These are NOT the SAME as distance-time graphs and have different rules!
The slope of a velocity-time graph equals the ___________________________
On velocity-time graphs a flat line is a ____________________________
A straight line on a velocity-time graph is _____________________________
If the slope is positive, the object’s speed is increasing
If the slope is negative, the object’s speed is decreasing

11.3 Questions
1. Describe the 3 types of changes in velocity:
2. What does the slope on a velocity-time graph give you?
3. What is instantaneous acceleration?
4. How are acceleration and deceleration related?
5. Two trains leave a station at the same time. Train A travels at a constant speed of 16 m/s. Train B starts at 8 m/s, but accelerates at a constant 1.0 m/s 2 . After 10 seconds, which train has the greater speed?
6. What force causes the acceleration of an object in free fall?
7. Answer the following questions about the two velocity-time graphs:
A) Graph A represents the motion of a downhill skier. How fast was the skier moving after traveling down the hill for 2.5 seconds?
B) In which graph does the object move at a constant speed for the first 4 second?
C) Graph B represents the motion of a mountain biker. What is the biker’s speed at 10s? At 20s?
D) Determine the acceleration of the biker during the 10s to 20s time period.
8. Light travels from a star to Earth at a constant 3.0 x 10 8 m/s. What is the acceleration of the light?
9. On a velocity-time graph, how would you show an object that is not moving?
10. Explain a situation where you can be accelerating even if the speed remains constant.
11. If the points on a velocity-time graph do not form a straight line, what can you say about the acceleration?
12. Complete the table by sketching the graph
Distance-Time Graph Velocity- Time Graph
At rest
Constant Speed
Acceleration

CHAPTER 11 STUDY GUIDE
1.
How fast is a passenger in a car traveling at a constant speed moving relative to the driver?
2.
A person drives 2 blocks north, then 3 blocks east, and finally 2 blocks south. a.
What is the driver’s total distance travelled? b.
What is the driver’s displacement?
3.
What is the result of combining displacement vectors of 1 km south, 5 km north, 6 km south, and finally 4 km north?
4.
Formula for speed-_____________________________________________________
5.
A car travels 275 miles in 2.5 hours, stops for 0.25 hours, then travels another 50 miles in .25 hours.
What is the car’s average speed?
6.
A flat, horizontal line on a distance-time graph means the object is _______________________.
7.
If an object travels 80 meters in 4 seconds, then remains at rest for the last second, what is the average speed?
8.
A change in velocity is a change in ___________________ OR _________________________
9.
Give an example of acceleration that is changing only due to a change in direction:
10.
An object moving at 30 m/s takes 6 s to come to a stop. What is the acceleration of the object?
11.
A car is moving at a constant speed of 10 m/s for 10 seconds, then steadily decreases speed until it comes to a stop at 30 s: a.
Sketch the graph b.
Describe the slope of the v-t graph for the first 10s: c.
What is the acceleration for the first 10 s? d.
Describe the slope of the v-t graph for 10s-30s: e.
What is the acceleration for the 10s-30s interval?
12.
Find the acceleration of an object whose velocity goes from 30 m/s to 10 m/s:

13.
T or F?: An object that is accelerating is always speeding up or slowing down.
14.
T or F?: An object at rest has an instantaneous acceleration of zero
15.
T or F?: Instantaneous acceleration is always changing
Fill in the blank:
16.
The equation, 𝑣̅ = 𝑑
, is the equation that defines ___________________ 𝑡
17.
A quantity that has magnitude and direction is called a ______________ quantity
18.
Slope on a d-t graph is _____________________ and Slope on a v-t graph is ______________________
19.
How fast velocity is changing at a specific instant is called ___________________________
20.
What is a suitable SI unit to express the speed of a racecar?
21.
What types of changes in motion cause acceleration? (Name three)
22.
A racecar is travelling around a track at a constant speed. Is the racecar accelerating?
23.
Objects in free fall experience constant __________________ due to _____________________
24.
Depending on your __________________________, the motion of an object may appear different
25.
The distance and direction of the line from an object’s starting and ending points is called __________
26.
The sum of 2 or more vectors is called the ____________________.
27.
A car’s speedometer measures ___________________________________.
28.
The difference between speed and velocity is that velocity includes ____________________.
29.
Use the VELOCITY-TIME GRAPH to answer the following: a) During which section is the object speeding up? _______ b) During which section is the object slowing down? ______ c) During which section is the object at rest? ______ d) During which section is the object travelling at a constant speed? _______ e) Find the acceleration during section A: