Calculating the speed and velocity of an object

Bellwork: Read page 451 Describing Motion and Speed Using Strobe Photos

Which plane is traveling faster? Explain how you interpreted the pictures.

A: Q Q Q Q Q QB: Q Q Q Q

Video

Brainpop!( Distance, rate and time)

Rate = ?

What is Speed?• Speed is a measure of the distance an object

moves in a given amount of time.• During a typical trip to school, your car will

undergo a series of changes in its speed.

Speed

Speed = distance travelledtime taken

Speed

Speed = distance travelledtime taken

seconds

meters

Meters per second (m/s)

Speed

Speed = distance travelledtime taken

hours

kilometers

Kilometers per hour (km/h)

Distance traveled?

What if we know the speed of an object and the time it moved for and need to calculate the distance traveled?

Distance traveled?

What if we know the speed of an object and the time it moved for and need to calculate the distance travelled?

Speed = distancetime

distance = speed x time

Time?

What if we know the speed and the distance traveled, how do we calculate how long (time) the journey took?

Time?

What if we know the speed and the distance travelled, how do we calculate how long (time) the journey took?Speed = distance

time

time = distance speed

triangle

s tx

d

If the distance is measured in meters and the time in seconds, -the speed will be in meters per second (m/s or m.s-1).

If the distance is in kilometers and the time in hours, -the speed will be in kilometers per hour (km/h)

EXAMPLES

Usian Bolt ran 100m in 9.58 seconds, what was his average speed?

10.43 m/s

Another example

A dog runs at a speed of 5 m/s for one minute. How far does he run?

Another example

A dog runs at a speed of 5 m/s for one minute. How far does he run?

Distance = speed x time = 5 m/s x 60s = 300 m

Another example!

A car travels at 30 km/h and covers a distance of 900 km. How long did it take?

Another example!

A car travels at 30 km/h and covers a distance of 900 km. How long did it take?

Time = distance/speed = 900/30 = 30 hours

Practice:Distance, Speed and Time

Speed = distance (in meters) time (in seconds)

D

TS

1. Laura covers 2000m in 1,000 seconds. What is her speed?

2. How long would it take to run 100 meters if you run at 10m/s?

3. Steve travels at 50m/s for 20s. How far does he go?

S = D/T = 2000m/1000s= 2 m/s

T = D/S= 100m/10m/s= 10s

D = S x T= 50m/s x 20s= 1000m

Speed and Velocity: Pg 455

What are the differences between speed and velocity?

What is Velocity?Speed in a given

direction is called velocity.

When you know both the speed and direction of an object’s motion, you know the velocity of the object.

Can we change velocity but not change speed?

The speed of this car might be constant, but its velocity is not constant because the direction of motion is always changing.

Now you try!

Practice Problems:Page 463# 1-5