How to Calculate the Speed of an Object Using Distance and Time

If you finish this lesson, you'll be able to calculate the speed of any moving object as long as you know how far it travels and how long it takes. This is a key skill in physics, useful for everything from solving textbook problems to understanding how fast a car is moving in real life.

The Basic Formula

Speed tells you how fast something is moving. The formula is:

$$\text{Speed} = \frac{\text{Distance}}{\text{Time}}$$

• Distance: How far the object travels (in meters, kilometers, miles, etc.)
• Time: How long the object takes to travel that distance (in seconds, minutes, hours, etc.)
• Speed: How fast the object is moving (usually in meters per second, m/s, or kilometers per hour, km/h)

Worked Example: Calculating Speed

Question: A cyclist travels 600 meters in 2 minutes. What is her speed in meters per second (m/s)?

Step 1: Write down what you know.

• Distance = 600 meters
• Time = 2 minutes

Step 2: Make sure your units match.

• Time is given in minutes, but we want speed in meters per second.
• 2 minutes = 2 × 60 = 120 seconds

Step 3: Plug the values into the formula.

$$\text{Speed} = \frac{600\ \text{m}}{120\ \text{s}} = 5\ \text{m/s}$$

Answer: The cyclist's speed is 5 m/s.

Real-Life Application

You use this calculation every time you check your average speed on a car trip. For example, if you drive 120 kilometers in 2 hours, your average speed is 60 km/h.

Common Mistakes and How to Avoid Them

• Mixing up units: Always check that your distance and time units match the speed units you want (e.g., meters and seconds for m/s).
• Forgetting to convert minutes to seconds: If you use minutes for time but want m/s, convert minutes to seconds first.
• Dividing time by distance: Remember, speed = distance divided by time, not the other way around.

Practice Question

A runner covers 2,000 meters in 8 minutes. What is her speed in meters per second?

Takeaway and Next Step

Now you can calculate speed as long as you know distance and time. If you want to practice more or get step-by-step help with similar problems, you can try the Solve tool.