PHYSICS PROJECT 1

Stage 1: Problem Identification

1. Introduction
In many rural areas, especially in Zimbabwe, cooking depends on firewood and charcoal. This leads to
deforestation, health risks from smoke, and rising costs.

2. Problem Identification
 Environmental harm – Deforestation and land degradation.
 Health issues – Smoke causes respiratory problems.
 High costs – Firewood and charcoal are expensive.
 Low efficiency – Traditional methods waste energy.

Statement of Intent
To design and build a low-cost solar cooker using materials like scrap metal, wood, and foil.

Solution Goals:

 Reduce use of firewood.

 Promote clean, affordable cooking.
 Teach students about solar energy.
 ·Use affordable, local materials.

2.Investigation of related ideas

1.PARABOLIC SOLAR COOKER

How it works:
It uses a curved, dish-shaped surface (like a satellite dish) covered with reflective material (e.g.,
aluminum foil or mirrors) to focus sunlight to a central point. A pot placed at that focal point gets very
hot, allowing fast cooking.

Advantages:

 Very fast cooking: Can boil water or fry food in minutes, like a gas stove.
 High temperature: Reaches much higher heat than other solar cookers.
 Versatile: Can cook many types of food – boiling, frying, grilling.
 Works in cold weather as long as there is sunlight.

Disadvantages:

 Needs frequent adjustment: You must move it often to track the sun.
 Risk of burns: Concentrated sunlight at the focal point is extremely hot.
 Harder to build: Needs a perfect curve and good materials.
 Costly if you don’t have a ready-made dish

2. Box Solar Cooker

How it works:
Looks like a closed box with a glass or clear plastic lid. Inside is black to absorb heat. Sunlight enters
the box, is trapped inside like a greenhouse, and reflectors (aluminum foil or mirrors) help direct more
sunlight in. Food cooks slowly inside.

Uses a curved, reflective dish (like a satellite dish) to focus sunlight on one central point. It reaches
high temperatures quickly. Can fry, boil, or grill food.Can fry, boil, or grill food.

Advantages
 Cooks food quickly (similar to a gas stove).
 Can fry, boil, or bake food.
 Works well in cold weather as long as there is sunlight.

Disadvantages
 Requires constant sun tracking for efficiency.
 Can be dangerous due to intense heat (risk of burns).
 More expensive and difficult to build than a box cooker.

3. Hybrid Solar Cooker

How it works:
It’s a solar cooker (often like a box cooker) but includes an electric or gas backup. So if there’s no
sunlight, the food still cooks using the backup power.
Advantages:
 Can cook anytime: Even on cloudy days or at night.
 Faster cooking: Heating element speeds up cooking.
 Reliable: Works daily regardless of weather.

Disadvantages:
 Expensive to build: Needs electric parts or gas lines.
 Less eco-friendly if backup is used too often.
 Not fully sustainable. If used with electricity or gas regularly, it defeats the purpose of solar
energy.
Stage 3. Generation of Ideas
1.Low-Cost Hybrid Solar + Fireless Cooker

Description:
This cooker uses solar energy to partially cook food, then the hot pot is placed in a well-insulated box
(like a hay box or fireless cooker) to finish cooking without more heat. No electricity or gas is used —
just insulation (blankets, straw, etc.).

Advantages:
 Fully off-grid — no gas or electricity needed.
 Keeps food warm for hours after cooking.
 Very cheap to make using cardboard, cloth, or straw.

Disadvantages:
 Only suitable for slow-cooking meals (stews, rice, etc.).
 Needs strong sunlight to heat pot first.
 Doesn’t work for frying or fast cooking.

2. Box Solar Cooker

Description:
This cooker is a well-insulated wooden box, painted black inside. It has a glass or plastic lid to trap
sunlight, and side reflectors made from foil or mirrors. Acts like a greenhouse to slowly cook food
inside.

Advantages:
Easy to build using wood, foil, and glass.
Can cook multiple meals at once — like rice, vegetables, or bread.
Safe and suitable for schools — no open flames.

Disadvantages:
 Takes a long time to cook (2–4 hours).
 Cannot fry food — only works for slow-cooking.
 Needs frequent repositioning to follow the sun.

3. Parabolic Solar Cooker

Description:
A reflective satellite dish focuses sunlight onto a small focal point, where a pot stand or tripod is
placed. A wooden frame supports the dish and allows it to tilt and rotate, tracking the sun for
maximum heat.

Advantages:
 High temperatures — can boil, fry, or grill food.
 Uses recycled local materials (mirrors, dishes, wood).
 Faster cooking compared to other solar methods.

Disadvantages:
 Dangerous to collect and attach mirrors.
 Wood can rot or attract termites.
 Needs manual adjustment every 30–40 minutes.

Stage 4: Development of Chosen Idea

1. Identification of the Choice

The chosen idea is the Parabolic Solar Cooker.

It was selected from three possible options (parabolic, boxed, and low-cost hybrid), because of its
high heat efficiency, ability to fry and boil, and its use of recycled local materials.
It uses a parabolic-shaped reflector (like an old satellite dish) that reflects sunlight to a central focal
point, where a pot is placed for cooking. The design maximizes solar energy and provides faster
cooking than the other two ideas.

3. Justification of the Choice

The Parabolic Cooker was chosen because:

 Higher cooking temperatures than the box and hybrid models – it can even fry food.
 More efficient — it cooks faster and uses concentrated solar rays better.
 Cost-effective — it makes use of local and recycled materials (e.g., satellite dish, mirrors, scrap
wood).
 Educational value — allows learners to explore real-life physics: reflection, focal points, and
energy transfer.

4. Refinements Made

Refinement 1: Focal Point Calculation for Maximum Heating

Using the parabola formula:

F=D^2/16d

Where:

D=1 meter
d=0.2 meters

F = 1^2/16x0,2 = 1/3.2 =0.3125 metres = 31.25cm

Refinement 2: Mirror Size Optimization

 Mirror pieces were cut into small 4 cm² tiles instead of larger ones.
 This reduces gaps between mirrors and increases reflection accuracy.
 Also makes it easier to glue them onto the curved dish surface.
Effect: More sunlight is focused and less light is wasted.

Refinement 3: Adjustable Wooden Stand

Designed a pivot-and-swivel base using:

 Door hinges (for up-down tilting)
 Bicycle bearings or rotating joints (for sideways rotation)
 A manual rope or rod lock system was added to keep the cooker pointed at the sun during
cooking.
Effect: Maintains sun alignment, ensuring continuous focus and better heat efficiency.

5.Overall Presentation or Impression of the Solution

The final solution — a Parabolic Solar Cooker made from a recycled satellite dish, mirrors, and wood
— successfully achieved the main goals of the project.
It provides a clean, cost-effective, and eco-friendly cooking method that reduces reliance on firewood
and electricity. The cooker reaches high temperatures quickly, making it suitable for boiling, frying,
and daily school use.
The design used locally available materials, making it affordable and easy to maintain. It also taught
students practical applications of physics concepts like reflection, focal points, and energy conversion.
Despite small challenges (e.g., mirror handling and wooden structure), the cooker:

 Performed effectively in sunny conditions

 Reduced firewood consumption at school
 Promoted sustainability and hands-on science learning

PRESENTATION OF THE FINAL SOLUTION

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EVALUATION AND RECOMMENDATIONS

1. Relevance to Statement of Intent

The project aimed to design a functional, low-cost solar cooker using locally available
materials (mirrors, scrap wood, satellite dish) to provide a sustainable cooking
method for the school.
The solution achieved this by:
 Using solar energy instead of firewood, reducing deforestation.
 Eliminating smoke, improving health and air quality.
 Lowering fuel costs for the school.
 Providing practical learning in renewable energy and physics.

So, the final product was fully aligned with the original goal and proved both
relevant and impactful.

2. Challenges Encountered and Recommendations

Challenge Solution/Workaround

Risk of cuts from broken mirrors Used thick rubber gloves and handled pieces
carefully

Wooden frame vulnerable

to rot and termites Applied weatherproof paint to prevent it
Final Recommendations:

· Add a backup heat source like a fireless cooker box or small electric heater for
cloudy days.
· Replace mirror pieces with aluminum sheets for easier handling and fewer injury
risks.
· Use metal for the frame instead of wood to improve long-term durability.
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