S10 U1C1L2.3 - Speed and Velocity

S10 U1C1L2.3 - Speed and Velocity

by David Victor Banares

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​The greater the distance traveled by an object in a given time, the greater is its average speed. A car that has traveled 80 km in one hour has lower average speed than an airplane covering 800 km in one hour. In either case, however, it is unlikely that a constant speed was maintained for one hour. The car may have to slow down on curves or hills or to stop for red lights or crossings; conversely, it may have picked up speed on open stretches and while overtaking other vehicles. Hence, we say the car has an average speed of 80 kilometers per hour.

​Speed

​is the rate at which distance is covered over time. (Scalar quantity-only tells the magnitude)

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average speed = 

total distance traveled /

elapsed time

Average speed is the rate at which total distance traveled varies with the total time taken.

​instantaneous speed

​Speed at an instant or at a point on the path.

​The speed that you see in the speedometer is an instantaneous speed.

Multiple Choice

What is speed?

• how far you go

• how much distance is covered over a period of time

• how fast you accelerate

• the change in the location of a object

Multiple Choice

A runner races in the 100 meter dash.  It takes her 10 seconds to finish.  What is her average speed?

• 10 m/s

• 1000 m/s

• 100 seconds

• 10 seconds

Multiple Choice

Total distance divided by total time is

• average speed

• constant speed

• instantaneous speed

• acceleration

Multiple Choice

When you look at the speedometer of your car, it tells you your....

• Average speed

• Instantaneous speed

​Velocity

​refers to the direction associated with speed

​Average Velocity

The average velocity of a moving body is defined as the displacement divided by the elapsed time:

Multiple Choice

Identify the physical quantity:     50 km/hr

• speed

• velocity

• direction

• time

Multiple Choice

Identify the physical quantity:     12 km from home to market

• speed

• velocity

• distance

• displacement

Multiple Choice

Identify the physical quantity:     220 km 30° NE

• speed

• velocity

• distance

• displacement

Multiple Choice

Identify the physical quantity:     80 km/h west

• speed

• velocity

• distance

• displacement

Multiple Choice

Velocity is both ____ and _____. 

• speed , direction 

• direction, mass

• volume, density 

• direction, magnitude 

​Calculating Velocity

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​Pause

​Go to your textbook and review sample question about velocity:

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​Nilo drives his van with an average velocity of 45.0 km/h along the North Expressway. How long will it take him to drive 350 km on a perfectly straight highway?

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​When done. Procedd to the next slide.

Multiple Choice

Nilo drives his van with an average velocity of 45.0 km/h along the North Expressway. How long will it take him to drive 350 km on a perfectly straight highway?

• .129 hours

• 7.778 hours

• 77.78 hours

• 12.9 hours

Open Ended

It took 2.50 h for a car to travel a distance of 150 km. What is its average speed?

Open Ended

A tourist bus moves at an average velocity of 60.0 km/h for 0.500 h. What is the total displacement of the bus?

Lesson ends here​

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