The average speed of an object is the distance it travels per unit of time, measured in metres per second (m/s). It is a scalar quantity.

The instantaneous speed of an object is its speed at a particular moment.

Manual timings include some timing errors. These can be due to reaction times or observing from incorrect positions.

Random errors are errors that vary from test to test in an uncontrolled way.

Measuring speed accurately

Science

In the Measuring and calculating motion unit, they will build on this knowledge to learn how to measure and calculate velocity and acceleration, and how to interpret velocity-time graphs. 

In the Forces unit, pupils learn to accurately describe and explain the actions of forces in a range of situations. 

This unit explores speed, forces, and motion, including effects on objects. It covers deriving equations, calculations, and distance-time graphs. Learn to use force arrows, identify balanced and unbalanced forces, and understand their impact on movement.

Moving by force

unpredictable difference between measurement and true value

a difference in a measurement of time and the true time

overall distance travelled divided by overall time taken

Select the reading that has a large timing error in this set of timing data.

Five different trolleys are rolled along a 3.0 m track. Their times are shown. Starting with the fastest, put them into order of speed.

Counting down before releasing the trolley and starting the watch together.

Observing directly across the finish line.

Using a stopwatch with a precision of 0.001 s.

Which of these will help to reduce timing errors in a trolley rolling experiment?

The calculated speed will be faster than the true speed.

The calculated speed will be slower than the true speed.

They will not be able to calculate a speed.

Due to a timing error a student measures a time that is longer than the true time. How will this affect the speed they calculate for a rolling trolley?

Making a video of the ball with a mobile phone

Suggest which of the following items would be the most accurate way of measuring the time taken for a ball to be thrown across the lab?

Match the units to the quantities they are used to measure.

Which of these equations shows how distance travelled can be calculated from average speed and time?

Starting with the slowest, sort these objects in order of speed.

A student measures how long a trolley takes to fall a distance of 1.5 m three separate times. Their readings are 2.5 s , 2.1 s, and 2.0 s. Calculate the average roll time.

A trolley was allowed to roll along a series of tracks of different steepness giving different average speeds. Starting with the slowest, sort the results in order of increasing average speed.

A toy car rolls through a distance of 3.2 m in a time of 1.6 s. Calculate the average speed of the trolley giving the correct unit.

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