Motion - Speed, Velocity and Acceleration

What does the slope of a line on a speed-time graph represent?

Slope = acceleration Rise/Run = change in velocity/time

What does the slope of a line on a distance-time graph represent?

Slope = speed Rise/run = distance/time

A car travels 100 km in 2 hours. What was the car's average speed? Don't forget your units!

Speed = distance/time S = 100 km/2 hours S = 50 km/hr

What is the acceleration triangle? How do you use it?

change in velocity = acceleration x time time = change in velocity /acceleration acceleration = change in velocity/time

What is the SI unit for speed?

meters/sec m/s A certain distance covered in a certain amount of time

What is the SI unit for acceleration?

meters/sec/sec m/s2 A change in velocity in a certain amount of tiime

In what ways can velocity change?

1. You can change speed 2. You can change direction.

In what ways can you change acceleration?

1. You can speed up 2. You can slow down 3. You can change direction

What is a reference point?

A "background" place or object that is used for comparison to determine if something is in motion or not. For example...compared to the tree, the car appears to be moving. (Tree = reference point; Car = object)

A bicyclist is pedaling at 20 m/sec. All of a sudden, a bee flies after him and tries to land on his arm. The bicyclist speeds up to 30 m/sec in 5 seconds. What was the bicyclist's acceleration? Don't forget your units!

Acceleration = (final velocity - initial velocity)/time a = (30 m/sec - 20 m/sec) / 5 sec a = 10 m/sec / 5 sec a = 2 m/sec/sec or 2 m/s2

What does a speed graph look like? What are the axes?

x-axis = time y-axis = distance

What does an acceleration graph look like? What are the axes?

x-axis = time y-axis = speed

What is velocity?

Velocity = Speed WITH DIRECTION!! In the picture to the right, the people are traveling at 75 km/hr in the FORWARD DIRECTION.