Unit 10 - Velocity and Momentum

Unit 10 - Velocity and Momentum

By S Harris

Question

​You are listening to the radio in your car and hear them say that a storm that is traveling at a speed of 20 km/h is east of your current location. Should you be worried about it?

Answer

You don't actually have enough information to know if you should worry (the reporter has only given you the speed of the storm). You would need to know the direction that the storm is traveling to determine your next steps.​

• you would need to know the velocity of the storm​

What is velocity?

Velocity is different from speed because it is a measurement of the speed of an object and the direction of the object's motion.

• ​it's units are m/s​

  • the same units as speed

• RECALL: speed is a measure of distance traveled over a certain amount of time

Velocity Continued

Velocity depends on speed (distance and time) and direction, which means:

• an object's speed can remain the same, but change velocity

  • this happens if the direction the object is traveling in changes​

  • example : race cars on a track

QUESTION:

Is it possible for two objects to have the same speed, but different velocities?

ANSWER:

Yes, if they are traveling at the same speed, but going in different directions, they would have different velocities because their direction of travel is different.​

What is momentum?

Momentum is the product of an objects mass and velocity (represented by the symbol p)​.

• Equation:

  • p = mass x velocity

  • p = mv​

Momentum Continued

An objects' momentum is always going in the same direction as its velocity.

• the table shows a few examples of objects and their momentums​

​Object Name	​Momentum (kg
​tossed baseball	​0.15
​a person walking	​100
​a car on the interstate	​45,000

Multiple Choice

Both vehicles are going 70 m/h south. Which one of the vehicles (the car or the semi-truck) has the larger momentum?

• the car

• the truck