What helps a racing car go fast?

This task is about features of a racing car that make it go faster.

There are some things that scientists have noticed that help make cars go faster.

What helps a racing car go fast?

Explain how these parts of the racing car can help it go faster.

Diagnostic and formative information:

The tables below broadly compare the types of responses made at the three different levels. Use the progressions to decide on next teaching points.

Tyres

Year 4	Most who responded correctly were able to incorporate simple references to science theory, mostly using the word "grip". The word "friction" was not used.
Year 6	Explanations using both observations and science theory increased in number from Year 4. Some students also mentioned that wide tyres provide more "balance".
Year 9	Explanations incorporating science theory increased from Year 6, but "grip" was still the most common word used. A few talked about "friction" and "traction". Some students also mentioned that wide tyres provide more "balance".

Shape

Year 4	Almost all correct responses were an observation e.g., helps it go through the wind. No references to wind resistance were made.
Year 6	Mostly observational, although a few attempted to include science theory in their explanations. One student mentioned "wind resistance", another used the term "drag".
Year 9	Mostly observational. More students attempted to incorporate science theory, but most of these were only partial explanations, and some contained misconceptions. Some students began using scientific terms such as drag, air/wind resistance and aerodynamics.

Spoilers

Year 4	Mostly observational, e.g., helps it stay on the road.
Year 6	Mostly observational.
Year 9	Mostly observational. A few students provided partial scientific explanations, and three students demonstrated a clear understanding of the science involved.

Low to the ground

Students considered two concepts in their explanations.
	Balance/centre of gravity	Aerodynamics/air pressure
Year 4	About half the students who gave correct or partially correct answer referred to it being harder to "tip over" and half of these explained this in terms of balance. Centre of gravity was not mentioned.	About half of the partially correct responses were about air not getting underneath.
Year 6	A far smaller proportion than year 4 students referred to balance. Two students mentioned gravity, but applied the concept incorrectly.	The majority still gave responses about the air not getting underneath. Some students mentioned that it kept the car sticking to the road, and a few attempted simple explanations, such as "if the air gets under the car it could lift it up".
Year 9	A similar proportion as Year 6 referred to balance. One student used "centre of gravity" to explain how speed around the track is increased.	The majority still gave responses about air not getting underneath. Some students mentioned that it kept the car sticking to the road, a few attempted simple explanations for how this worked, and 2 gave detailed and correct explanations. A substantial number of students referred to wind resistance, interpreting "low to the ground" as the total car shape.

10 of the 145 Year 4 students who trialled this resource stated that being low to the ground meant that the car could go under the wind. This response may be due to either:

a misconception about wind, i.e., it is not present at ground level; or
a partial understanding of aerodynamics.

At Year 9, 5 of 176 students made this response (this drop is not statistically significant).

Another common response was "no air can get under the car". Although not scientifically correct, this may signal a beginning step to understanding that there is an area of low air pressure under the car. Year 9 students were more likely to give the beginnings of a theoretical explanation about the lack of air underneath the car. However, 13 Year 9 students still made reference to better handling without any explanation, 66 gave incorrect responses, and 17 did not answer. Not surprisingly, no students at any year level mentioned that an area of low pressure is created under the car.

Other interesting points

Year 4	Seven students equated lowness with lightness. Aesthetics was commonly given as a reason e.g., "to make it look cool", "easier to get in". Many responses just repeated the question e.g., "being low to the ground makes it go faster".
Year 6	Two students equated lowness with lightness. A number of students thought of lowness to the ground as a factor in reducing air resistance, rather than also considering the shape.
Year 9	Only two students were able to give clear answers that explained the science for all four questions (both boys). Refer to Examples of student responses. Year 9 students were more likely to use scientific terms, but sometimes these were used incorrectly or without enough explanation to show that they understood the term. Many responses just repeated the question, as in Years 4 and 6.

Examples of student responses

The samples of student responses (Year 9) can be used:

by teachers, as examples of possible student responses;
by students, to self- assess their work, or as the basis of a class/group discussion.

These can be reproduced separately for sharing. Go to Student work samples.

Next steps
The context of the technology of racing cars provides a rich source of science to investigate. Some of the science concepts that could be explored are:

forces and motion
down forces
friction
centre of gravity/balance
air pressure
air resistance
aerofoils/wings

Especially with younger students, consider focusing on one of these concepts rather than trying to cover them all. From the trial, it appears that the least difficult concept, or the one that students are most familiar with, is that the aerodynamic shape decreases wind resistance. However, few students at any level included explanations about how this works. This may be a sensible starting place for further exploration.

Student work samples

Example 1
Wide tyres:
Increases the amount of rubber in contact with the road, which gives better grip at high speed and cornering.

Streamlined shape:
Cuts through the air more efficiently, which reduces drag.

Spoilers:
Are like an upside down aeroplane wing, which push the car onto the road.

Low to the ground:
Lowers the centre of gravity, which makes the car more stable. It also reduces the amount of air flowing under the car.

Example 2
Wide tyres:
The wide tyres cover more track (more traction). Tyres called slicks have no tread, so the whole tyre is on the ground.

Streamlined shape:
Air goes quickly over the body. The streamline effect makes the car cut through air.

Spoilers:
Due to the wing's angle, the air creates down force as it passes over the car (more traction). These wings do the exact opposite to a plane's wings.

Low to the ground:
If too much wind gets underneath the body then it may create lift.

NOTE: Two levels of answers are supplied. As students progress, a curriculum expectation is that they are able to include more science theory in their answer.
Explanations linked to observations	Explanations linked to science theory
Tyres: Fast cornering/fast acceleration	Achieves a better grip with the track/provides better traction/greater contact surface/increases friction or Provides more stability/more balanced
Streamlined shape: So the car passes through the air more easily	To reduce friction/reduce wind or air resistance [Do not accept "It is aerodynamic", unless accompanied by an indication of what this means.]
Spoilers: Hold car down on the track	To increase downwards force for greater traction. [Some students may compare with aircraft wings.]
Low to the ground: Can go around corners faster/ less chance of rolling when cornering/ prevents air going under the car	Lower centre of gravity/better balance when cornering or Prevents lift/creates an area of low pressure under the car, which produces a "suction" effect

	Y4 (11/04)	Y6 (11/04)	Y9 (3/05)
Tyres Streamlined shape Spoilers Low to the ground	very difficult difficult very difficult very difficult	difficult easy very difficult difficult	moderate easy very difficult moderate

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