Bellringer 8/30

What is the difference between speed and velocity?

Today’s Target…

I can use observations and appropriate tools to document the position and motion of objects. This means I can make observations about how an object’s motion changes.

REVIEW

What is motion? How do we know an object is in motion? How do we measure motion? What is the difference between speed and

velocity? How do we find speed?

Acceleration

Consider this: a car is stopped at a red light, when the light changes the driver gently steps on the accelerator and the car speeds up or accelerates

In everyday language acceleration means “the process of speeding up”

Acceleration

Acceleration is the rate at which velocity changes Remember that velocity is speed and direction Acceleration is

– increasing speed– decreasing speed– changing direction

Increasing Speed

Any time the speed of an object increases it experiences acceleration

What are some examples of acceleration?– A car that moves from a stopped position– Runners taking off

Decreasing Speed

Decreasing speed is also acceleration Called negative acceleration or deceleration What are some examples of deceleration?

– A ball rolling to a stop– A car coming to a red light– An airplane landing

Changing Direction

Remember that velocity involves both speed and DIRECTION, so a change in direction is also acceleration

You may think that a car traveling at constant speed does not accelerate, but actually it does because it will change directions!

Changing Direction

Examples:– Race car drivers rounding a turn– Any circular motion

The seats on a Ferris wheel

Did you get it?

How is it possible for a car to be accelerating if its speed is steady at 65 mph?

Determining Acceleration

Speed Time

60 km/h 0s

62 km/h 1s

64 km/h 2s

66 km/h 3s

Determining Acceleration

Speed Time

12 m/s 0s

8 m/s 1s

4 m/s 2s

0 m/s 3s