Please provide a rating, it takes seconds and helps us to keep this resource free for all to use
In addition to the revision notes for Speed and Velocity in 1 Dimension on this page, you can also access the following Kinematics learning resources for Speed and Velocity in 1 Dimension
| Tutorial ID | Title | Tutorial | Video Tutorial | Revision Notes | Revision Questions | |
|---|---|---|---|---|---|---|
| 3.5 | Speed and Velocity in 1 Dimension |
In these revision notes for Speed and Velocity in 1 Dimension, we cover the following key points:
When combining the moving distance and time we obtain a Kinematic quantity known as Speed (v).
By definition, Speed (v) is the Distance travelled by an object in a given time (sometimes we say "in the unit of time" instead of "in a given time").
Mathematically, we can write
Since (in the SI system of units) the Displacement is measured in metres and Time in seconds, the unit of speed is
The average speed < v > of an object refers to the total distance it travels divided by the time elapsed.
Mathematically, we write
Speed is a scalar quantity as it is obtained by dividing two scalars: distance and time of motion.
Instantaneous Speed (v) is another important concept used in Kinematics. It shows the actual speed by which an object is moving.
To calculate the instantaneous speed of an object, we take a small portion of distance and divide it by the corresponding (small) time interval. The smaller the distance (and the time interval) used, the more accurately we can measure the speed for that specific time.
The equation of instantaneous speed v is
where Δs represents the small distance considered and Δt the time interval during which the event occurs.
When dividing Displacement and Time, we obtain a new physical quantity known as Velocity.
Velocity is a vector quantity and it is denoted by v⃗. Its formula is
In symbols (in one dimension) the above equation is written as
Since Displacement is measured in metres and Time in seconds, the unit of Velocity is [m/s] just like the unit of Speed.
It is obvious Velocity is a vector quantity as it is obtained by dividing a vector by a scalar.
If we want to calculate the average and instantaneous velocity, the approach is the same as for average and instantaneous speed. Thus, Average Velocity < v⃗ > represents the total Displacement divided by the total Time taken. The concept of average velocity is particularly useful when dealing with non-uniform motion.
Mathematically, we have:
As for the Instantaneous velocity v⃗, again we take two neighbouring values for Position and Time. In this way, we obtain one interval for each quantity, namely ∆x⃗ and ∆t. Therefore, we obtain the equation
A very important rule in Kinematics states that:
The slope (gradient) of the Position vs Time graph gives the Velocity.
Enjoy the "Speed and Velocity in 1 Dimension" revision notes? People who liked the "Speed and Velocity in 1 Dimension" revision notes found the following resources useful:
Please provide a rating, it takes seconds and helps us to keep this resource free for all to use
We hope you found this Physics tutorial "Speed and Velocity in 1 Dimension" useful. If you did it would be great if you could spare the time to rate this physics tutorial (simply click on the number of stars that match your assessment of this physics learning aide) and/or share on social media, this helps us identify popular tutorials and calculators and expand our free learning resources to support our users around the world have free access to expand their knowledge of physics and other disciplines.