1. Difference between speed and velocity

2. Objectives 1. Define velocity
2. Differentiate between speed and velocity
3. Explain the difference between instantaneous and average speed and velocity
4. Determine average velocity
5 Use position-time graphs to determine instantaneous and average velocities
6. Write the equation of motion for average velocity

3. Difference between speed and velocity
Velocity is different than speed.
While speed describes only how fast an object is moving, velocity gives both magnitude and direction.
For example, "5 meters per second" is the speed of a moving object ,whereas "5 meters per second east" is a vector.
Does this sound familiar?
Explain.

4. Things to agree on: Displacement = ∆d= df – di
Time interval= ∆t= tf – ti
For a uniform motion:
The position time graph is a straight line
Slope= displacement/time
= ∆d/ ∆t _
Average Speed= s =absolute value of the slope.
Average speed= distance /time _
4. Average Velocity= v=slope.
y- intercept= initial vector position .
A steeper line represents a greater speed and velocity ( as shows fig 2-20 p:43 on your textbook)
Application:
Find the average speed, average velocity and initial vector position of the moving object whose motion is represented by the figure at the right.
Write an equation representing the motion.

5. APPLICATION
Find the average speed, velocity and initial vector position of the motion represented by the following position-time graph.
Write the equation of the motion
Solve question p 45 no.27

6. Look at the following motion diagrams representing the motion of two cars
Plot the position-time graph for each car.
Find the slope for each line.
What is the speed for each motion
What is the velocity for each motion.
5. Find the initial vector position for the two cars. Write the equation of motion for each car.
Where and when the two cars meet?
Application:
Find the average speed, average velocity in figure 2-21 page 44 in your textbook.
Draw a corresponding motion- diagram for the moving object.

7. Difference between velocity and speed
Conclusion:
To have a constant velocity, an object must have :
constant speed
motion in a constant direction. Constant direction means a straight line and constant orientation.
Application
The figure at the right shows the motion of a car in a roundabout. Conclude.

8. Solve Questions p:45 no.35,26 & 27 + p53 no.49-51
Conclusion
Speed is how fast an object moves. It only has a magnitude. It is a scalar In a position-time graph of a linear uniform motion, the average speed is the absolute value of the slope.
Velocity is the speed of an object in a given direction. It has a magnitude and direction. It is a vector. In a position- time graph, the average velocity is equal to the slope.
Application:
Solve Questions p:45 no.35,26 & 27 + p53 no.49-51

9. The following Diagram represents the motions of two moving objects
The following Diagram represents the motions of two moving objects. Answer the below questions.
What type of motion is represented by each object?
Calculate the average speed of each object
Do the two objects have the same velocities? Explain.
Calculate the instantaneous speeds for each object between 0.1 s and 0.2 s.
5. Conclude.

10. Difference between average velocity and instantaneous velocity_
Average speed= s = distance
time __
V= displacement/time= ∆d/∆t
Is the average velocity during the whole path
It has the direction of the motion
Represents the velocity at a particular moment.
It has the speed and direction of the moving object at a certain moment.
Assessment:
Solve questions II and III

11. Uniformly accelerated motion
Velocity is not kept constant
Velocity –time graph is a straight line
Slope= velocity change=
time interval
=∆v=aceleration (m/s2) ∆t
equation: _
V= at+ vi
Application:
Find the equation of velocity of the motion represented in the figure, Find velocity at t= 1 s.
Find the time when velocity is 12 m/s.

12. Application
Find the equation of velocity of the motion represented in the figure.
Find velocity at t= 1 s.
Find the time when velocity is 12 m/s.

13. Look at the following diagram and answer the below questions
Find the average speed of object A and B
Represent the average velocity for A and B by corresponding vectors.
Find the instantaneous velocities at instant 0.1 and 0.5 s for every object. Conclude.
4. What type motion is represented by each object?
Calculate the value of the velocities at instant s for each object
Draw for each object the position-time graph
Draw for each object the velocity-time graph.
Find the acceleration for each object
Write the equation of motion for object A
Write the equation of each object.
Write the equation of motion of object B

14. Uniformly accelerated motion
Velocity is not kept constant
Velocity –time graph is a straight line
Slope= acceleration

15. Equation of a Linear uniform motion
Position time graph line of best fit:
Position-time relationship:
Equation:
where: the average velocity represents
and the initial vector position represents
So the equation would be:
Application:
Find the equation of the the motion represnted by the previous graph.
Solve page 53 no 54

16. For next time: Continue solving the worksheet
Download PowerPoint presentation on your macbook from wikispaces.
Quiz next lesson sections 1.3 and 2.2
Homework page 53 no.56 & 57