Chapter 10

Speed measures how fast position changes

Position can change at different rates.

• Speed is the measure of how fast something moves or the distance it moves in a given amount of time.

• The greater the speed an object has, the faster it changes position.

• Speed can be calculated by dividing the distance that an object travels by the time it takes the object to cover the distance.

• Formula• Speed = distance S = d

time t

Practice Problems

• A wheelchair racer completes a 100- meter course in 20 seconds. What is his speed?

• A man runs 200m in 25s. What is his speed?

• If you travel 100m in 50s, what is your speed?

Distance-Time Graphs

• You can see how both distance and speed change with time.

Practice Problems

• Page 3241. What is the speed of the zebra during the

20s to 40s time interval?

2. What is the speed of the zebra during the 40s to 60s interval?

Velocity

• Velocity is a speed in a specific direction.

• Give an example.

Vector

• A vector has both size and direction.

• Velocity is a vector quantity.

• Speed is not.

Velocity vs. Speed

• Read the two paragraphs on this example.

• Examine the picture at the top of page 327.

• Use a Venn diagram to compare and contrast speed and velocity.