A speed camera is used to measure speed of vehicles on roads. It captures images of any vehicle exceeding the speed limit of the road.

A radar gun uses shifts in the frequency of reflected radio waves to measure the speed of objects.

A light gate can be used to measure speed. It uses an infrared beam to turn a timer on and off as an object passes through.

Automated measurement of speed

Physics

Different speeds (v=x/t)

Measuring instantaneous speed practical (v = x ÷ t)

Measuring instantaneous speed analysis (v=x/t)

Displacement and velocity as vectors: including circular motion

Velocity on displacement-time graphs (v = x ÷ t)

Calculating from displacement-time graphs: including tangents (v = x ÷ t)

Calculating acceleration (a=(v-u)/t)

Measuring acceleration practical (v=x/t, a=(v-u)/t)

Measuring acceleration analysis (v = x ÷ t, a = (v – u) ÷ t)

Velocity-time graphs: acceleration and distance travelled (a=(v-u)/t)

Calculating from motion graphs: including displacement (a=(v-u)/t and v=x/t)

Motion calculations: including complex ones (a=(v−u)/t, v²−u²=2ax & v=x/t)

In the Energy of moving objects unit, they will build on this knowledge to learn how to calculate the amount of energy of objects have because they are moving, stretched or in a gravitational field; and to calculate energy transfers using knowledge of energy conservation and dissipation.

In the Moving by force unit, pupils learnt how to calculate speed and describe motion using distance-time graphs, apply Newton’s First Law of motion and calculate the amount of energy needed to move an object to a new position.

This unit covers vector-scalar distinctions in displacement, distance, velocity, and speed. It explores speeds, acceleration, motion graphs, and formulas for uniform and non-uniform motion. It also includes understanding circular motion and conducting accurate measurements, and calculations.

Measuring and calculating motion

Physical activity and equipment requiring safe use

sends signals to a timer when a passing object cuts its infrared beam

sends out sound pulses and the reflections from an object are detected

uses changes in frequency of reflected waves to measure speed

takes photos of road vehicles a short time apart

Match each of the following measuring devices to its description.

A student measures the time taken for a trolley to travel down a ramp and get these measurements: 0.19 s, 0.18 s, 0.26 s, 0.17 s. 
Which of the following mean times should the student record?

A trolley with a card attached travels through a light gate, which measures the time for the card to pass through. 
Which of the following statements is correct if the trolley moves faster?

A pair of speed cameras take photos of a car 0.50 s apart. The photos show that the car travelled 12 m during this time. The speed of the car is {{}} m/s.

A motion sensor sends out sound pulses. The pulses reflect off an object and return to the sensor after 0.0040 s. 
How far is the object from the sensor? 
The speed of sound in air is 330 m/s.

A trolley has a card of length 15 cm attached to it. The trolley passes through a light gate and the card cuts off the beam for 0.20 s. 
Which of the following is the speed of the trolley in cm/s?

It is a quantity that has magnitude (size) and direction. 

It is a quantity that has only magnitude (size) and not direction.

It is a quantity that has only direction and not magnitude (size).

It is a quantity that has no direction and no magnitude (size).

Speed is a scalar quantity. Which of the following describes a scalar quantity?

Match the the following objects with the example speeds.

speed = $$ 80 \text{ m} \times 20 \text{ s}$$

speed = $${ 80 \text{ m} \over 20 \text{ s}}$$

speed = $${ 20 \text{ s} \over 80 \text{ m}}$$

A dog runs 80 m in 20 seconds. 
Which of the following calculations would give the speed of the dog?

A hot air balloon flies at a speed of 15 km/h for 5 hours.
Which of the folloiwing is the distance it travels?

A sound waves takes 30 s to travel 45 000 m through water.
Which of the following gives the speed of sound in water?

A dynamics trolley is rolled down a ramp reaching a speed of 2.4 m/s.
Calculate the time it will take for the trolley to pass between a pair of markers which are 20 cm apart.

Starter Quiz

Speed is a scalar quantity. Which of the following describes a scalar quantity?