BeginnerTopic 3 of 102Manufacturing, Robotics & Systems
Problem solving and estimation
Back-of-envelope calculations check plausibility before detailed work.
In depth
Estimation (Fermi problems) provides order-of-magnitude answers to check models and feasibility; structured problem solving: restate, diagram, list knowns/unknowns, choose principles, solve symbolically, check units and reasonableness. Sensitivity analysis shows which inputs matter.
Key points
- Back-of-the-envelope calculations
- Dimensional checks
- Limiting cases
ExampleEstimating that a house uses about 30 kWh of electricity per day for sizing solar panels.
What is Problem solving and estimation?
Back-of-envelope calculations check plausibility before detailed work.
Why is it important to understand problem solving and estimation?
Quick estimates catch gross errors before detailed work begins, so they are one of the most valuable habits an engineer can build.
How do I make a good estimate?
Round the numbers to convenient values, use known reference quantities, and check the answer against physical intuition and units.
What is a Fermi estimate?
A method of estimating a quantity by breaking it into factors that can be guessed reasonably, which gives an answer within an order of magnitude.
How is Problem solving and estimation used in practice?
Typical applications include checking whether a claimed motor power is plausible for a lifting task, estimating the mass of a steel beam to see if a crane can lift it and sanity-checking a simulation result against a rough hand calculation.
What should I learn before Problem solving and estimation?
Study "Engineering design process" first (topic 2 of 102 in Manufacturing, Robotics & Systems). It covers the groundwork this topic builds on.
What are the key points of Problem solving and estimation?
Back-of-the-envelope calculations. Dimensional checks. Limiting cases.
Can you give an example of Problem solving and estimation?
Estimating that a house uses about 30 kWh of electricity per day for sizing solar panels.
What comes after Problem solving and estimation?
The next topic is "Engineering ethics", which builds directly on this one.
How difficult is Problem solving and estimation?
It is classed as Beginner in Manufacturing, Robotics & Systems (topic 3 of 102). It is an entry-level topic. It relies only on basic school mathematics and the ideas introduced earlier in this discipline.