In our Design and Technology class this week we were reminded of the importance of basic calculations when designing. The lecture was taken by Ben Craven. Using even the most basic of calculations can we determine the practical feasibility of our idea.

An idea was proposed to harvest the energy of shutting a filing cabinet

filing Cabinet calculation1


This calculation was very optimistic and very rough (as it should be) but it was a very quick way to assess that the idea was not going to work.

Important definitions. Precision – decimal places. Accuracy – how close to the real answer. Can be easily mixed up .

By incorporating the use of numbers and basic calculations in the early stage it can avoid putting time and effort into a design that will not work. Some examples are shown here. Including  Gravia


Similar to this proposal current proposal.

Incorporating early basic calculations is something I will now incorporate more into my design work.

It is good to have an idea of values and to quantify them eg time mass and density. I plan to build up a list of common values to help with these calculations.

Minute = 60s

Hour    = 60m   = 3600 s

Day     = 24h    = 1440m = 86,400

Week  = 7d      = 168h = 10,080m = 604,800s

Month = 30d    = 720h = 43200m = 2,592,000s

Year   = 365d  = 8,760h = 525,600m = 31,536,000s


Human – 70 kg

Small car – 1000 kg

Bag of flour / 1 litre of water – 1kg

Density values here and here

Lots more material properties here

Picture credit –