SLOWLY UNCOVERING VELOCITY…. 8.1 Continued: POSITION – TIME GRAPHING WITH UNIFORM MOTION

Objectives Explain the relationship of displacement and time interval to velocity for objects in uniform motion  Define displacement (change in position), time interval, and velocity  Analyse graphically the relationship between displacement and time interval for an object travelling in uniform motion  Calculate the average velocity, displacement, and time interval for an object in uniform motion, given appropriate data

CALCULATING THE SLOPE OF A POSITION TIME GRAPH Imagine two situations; A) Boy A walks 10 meters every second. B) Boy B walks 5 meters every second. Lets draw out what these position – time graphs would look like on the board.

EXAMPLE #1 Lets look at an object that is in uniform motion. This means the objects distance increases at the same rate for each time interval. In our example, every second the car moves 20ft. Lets graph this on the next slide.

A constant slope indicate uniform motion.

Reference Point: Also known as the ‘origin’, the reference point is needed so we know which way is positive, which way is negative, and where zero is.

POSITIVE SLOPE Positive Slope: The object is moving in the positive direction, and its position is increasing with time. This also means that the object has a positive velocity (it has a speed in the positive direction)

POSITIVE SLOPE Which is the moving the fastest? C Which starts at the origin (reference point)? A & B Are they all moving in the same direction? Yes – but ‘C’ starts at a different position. ABCABC

NEGATIVE SLOPE Negative Slope: The object is moving in the negative direction, and its position is decreasing with time. This also means that the object has a negative velocity (it has a speed in the negative direction)

Which is the moving the fastest? C Which starts at the origin (reference point)? A & B Are they all moving in the same direction? Yes – but ‘C’ starts at a different position. NEGATIVE SLOPE ABCABC

ZERO SLOPE Zero Slope: The object is at rest. The object is not moving. The position is not changing.

ZERO SLOPE Which is the moving the fastest? None of them are moving. Which is at rest at the -4m position? C Which is at rest at the reference point? B ABCABC

RECAP ON UNIFORM MOTION Distance changes equally in each time interval. Velocity is constant (meaning that the slope of a position time graph is constant)

HOMEWORK Read section 8.1 in Textbook. (Depends) Page 355 in Textbook. Q#1-7 (10 – 15 min) Page 361 in Textbook. Q#11 – 13 (5 min)