Acceleration Ch. 10.2

Objectives Describe the concept of acceleration as a change in velocity. Explain why circular motion is continuous acceleration even when the speed does not change. Calculate acceleration as the rate at which velocity changes. Graph acceleration on a velocity-time graph.

This Graph Shows Constant Velocity 2. Constant Increasing No Velocity 1. 3. Answer Now 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30

This Graph Shows No Velocity 1. Constant No Velocity Increasing 2. 3. Answer Now 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30

What is the distance a man can run in 1 hour if he runs at 7 mi/hr? 7 km 7 m 7 mi Answer Now 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30

What is the Velocity of a Plane that Travels 500 mi in 1 hour 500m/s 500 mi/hr 500 km/hr Answer Now 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30

Using the Conservation of Momentum if car has the momentum of 50 kg Using the Conservation of Momentum if car has the momentum of 50 kg*m/s and a man is in the moving car the man has? 50 m/s 50 kg 50 kg * m/s Answer Now 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30

final velocity – initial velocity Acceleration Acceleration = change in velocity divided by the time interval in which the change occurred. Acceleration = a = final velocity – initial velocity time vf – vi t

Units Acceleration = Vf – V i t Units = m or m s2 s * s

Acceleration Acceleration = rate at which velocity changes over time Quick time movie acceleration Acceleration occurs when there's a change in Speed Direction Or both change

Uniform circular motion is constant acceleration. QT Centripetal Acceleration Video of bucket and water having centripetal acceleration

Acceleration Acceleration can be determined from a graph QT Graphical Representations of Accelerations

Acceleration can also be determined from a velocity-time graph A straight line with slope = constant acceleration Slope of the line = acceleration

Horizontal line = constant speed, no acceleration or deceleration.

Examine the following graph.

A negative slope indicates that an object is slowing down or decelerating.

Calculating Acceleration Acceleration is the rate at which velocity changes. Acceleration Equation (for straight-line motion) QT Distinguishing B/W Velocity and Acceleration QT Average Acceleration SI Units = m/s2

The Top Thrill Dragster at Cedar Point goes from 0 m/s to 53 The Top Thrill Dragster at Cedar Point goes from 0 m/s to 53.6 m/s (120 mph) in 4 seconds. What is its acceleration? Given: a = Vf = V i = t = Algebra: Substitution:

A car traveling home at a velocity of 15 A car traveling home at a velocity of 15.6 m/s slams on its brakes and comes to a stop to avoid a dog. If it takes 5 seconds to stop, what is the cars acceleration? Given: a = Vf = V i = t = Algebra: Substitution:

In what direction is the car accelerating? How can you tell mathematically?

A Porsche Boxster has an acceleration of 4. 51 m/s2 A Porsche Boxster has an acceleration of 4.51 m/s2. If the car starts from rest how much time would it take for the vehicle to reach a speed of 11.3 m/s? Given: a = Vf = V i = t = Algebra: Substitution:

A golf ball thrown from the top of the sears tower accelerates at 9 A golf ball thrown from the top of the sears tower accelerates at 9.8 m/s2 toward the ground and lands on the pavement 9.2 seconds. If the ball’s final speed is 93.0 m/s what was the speed with which the ball was initial thrown? Algebra: Substitution: Given: a = Vf = V i = t =