1. VELOCITY & ACCELERATION Objective 4 Definitions: Velocity – how fast an object is moving and in what direction Speed - how fast an object is moving Acceleration – the rate at which the velocity of a moving object changes when either slowing down or speeding up Distance – the length of space between 2 points Free fall – accelerated motion that happens when an object falls with only the force of gravity acting on the object

2. VELOCITY & SPEED Look at the definitions of speed and velocity – what is the difference?

3. VELOCITY & ACCELERATION Look at the units for velocity and acceleration – what is the difference? https://www.youtube.com/watch?v=m1CQFGS6DO4

4. DESCRIBE THE MOTION OF THE CAR

5. IMPORTANT NOTES ON VELOCITY, SPEED, AND ACCELERATION Negative velocity means the object is moving backwards To calculate speed (s), you measure the distance, d, the object has traveled and the time, t, the object used to travel that distance. s= distance traveled = d timet s= distance divided by time When you calculate speed or calculate the average y- our answer cannot have more decimal places than the original numbers. On a speed versus time graph, a slope of 0 means there is no acceleration Negative acceleration means the object is slowing down & positive acceleration means the object is speeding up

6. PRACTICE CALCULATING AVERAGE AND SPEED, S TrialDistance (cm)Time (s)Speed, s (cm/s) Trial 1 Trial 2 Trial 3 Average s= distance traveled= d timet What is the precision of the stopwatch and tape measure? Acceleration?

7. LAB QUESTIONS Questions about the activity 1.Draw a forces diagram of the marble rolling down the ramp and a forces diagram of the marble falling to the floor. 2.In which section, along the PVC tube of dropping to the floor, was the marble’s speed the highest? Explain why this might have occurred. 3.Describe the motion of the marble in terms of Newton’s Laws. Questions using the graph 1.Calculate the speed of the marble from 0 to 7 seconds. 2.Discuss what you think occurred between 21 and 28 seconds?