12.1 - distance and time

• Distance is commonly measured in

metres (m).

• Distances between two points can

• Time (t) is the duration of an event.

• Time is often referred to as a and given the symbol t.

DO QUESTIONS 1-7 pg. 345 CYU

12.1 - Distance and Time12.1

VOCABULARY

time interval

slope

Period & Frequency

• A period (T ) is , such as

a pendulum swinging.

• It is related to frequency as:

Read Sample Problem #1 p. 343 then DO CYU #8-10 p. 345

• By relating time and distance, we can determine speed, which is the distance an object travels (d) divided by the time interval (t).

• The average speed of an object is the total distance the object travelled divided by the total time taken.

• Instantaneous speed

• For an object travelling at a constant speed (i.e. uniform motion), the average speed is equal to its instantaneous speed.

12.2Speed12.2

VOCABULARY

speed

average speed

instantaneous speed

Graphs are used to

***Be sure to really think about what the graph ACTUALLY represents***

Recall x and y

• A distance–time graph has distance on the y-axis and time on the x-axis.

• The slope of a line on a distance–time graph is .

• The units for the slope would be metres/second (m/s), the same as speed.

Graphing Distance and Time12.3

Do CYU 12.2 p. 350

• We can calculate the instantaneous speed of an object at a particular time by calculating the

to the line of the distance–time graph of the object’s motion.

Graphing Distance and Time12.3

• Just as we can use distance and time data to construct a graph, we can derive information about distance, time, and speed from a graph.

Calculate:1.The distance travelled between t=0.5hr and t=1.25 hr2.The average speed over the first 1.75 hr3.The speed the car is travelling at at t= 0.25 hr and also t = 2.25 hr4.In words write a description of the cars movement over the 2.5 hr interval in terms of speed, time and distance

12.4-Displacement, Time, and Velocity• Quantities can be either scalar

or vector.

• Scalar quantities only have magnitude, which is a number with a unit.

• Vector quantities have both a magnitude and a direction.

• An object’s speed and velocity can be described in different ways.

• For example, average speed or velocity, instantaneous speed, and uniform motion (constant speed or velocity).

• Distance and displacement are similar, but not identical concepts in science.

• Distance is a scalar quantity (magnitude only).

• Displacement is a vector quantity (magnitude and direction)

• The displacement of an object is its change in position in relation to a point of reference.

Displacement and Velocity12.4

VOCABULARY

scalar quantity

displacement

vector quantity

velocity

uniform motion

12.4Displacement, Time, and Velocity• The motion of an object can be

described by displacement, time, and velocity.

• Distance and displacement are similar but not identical concepts in science.

• Speed and velocity are also similar but not identical concepts.

1

• Speed and velocity are also similar, but not identical concepts.

• Speed is a scalar quantity (magnitude only).

• Velocity is a vector quantity (magnitude and direction).

• Velocity is the rate of change of displacement and is given by the equation:

• The slope of the line of a position–time graph is equal to the velocity of the object.

Displacement and Velocity12.4

VOCABULARY

scalar quantity

displacement

vector quantity

velocity

uniform motion

Displacement, Time, and Velocity• Distance–time graphs and position–time

graphs can visually display information about an object’s motion.

• The slope of the line is equal to the speed or velocity of the object.

• If the slope of the line is changing, the speed or velocity is not constant.

• If the slope the line is constant, the object is travelling at constant speed or velocity.

12CHAPTER

Displacement, Time, and Velocity12

Key Ideas

CHAPTER