How do I find an area in m^2 when I'm given lengths in cm?

its tempting when we're given a length in cm - let's use a radius for example - to simply square the number of cm. However this can lead you into traps. Take a circle with radius 5cm. We know that A=pir^2. It is therefore tempting to say that the Area is pi25, getting 78.5 cm^2. So far, this is correct. The issue comes when we say that 78.5cm^2 is therefore 0.785m^2. But if we imagine our radius 5cm circle in one m^2, this obviously isn't right. To help avoid this, change the units to m before you do any calculation. 5cm=0.05m. So we do A=pi0.05^2 = pi0.0025 = 0.00785m^2. This, now, is the correct answer.

Answered by Lauren M. Physics tutor

1904 Views

See similar Physics A Level tutors

Related Physics A Level answers

All answers ▸

What is an inertial frame of reference?


A gold leaf electroscope with a zinc plate top is charged by briefly connecting it to the negative electrode of a high-voltage supply. Explain how the gold leaf will appear and how the leaf can be caused to drop again.


How does the photoelectric effect (gold leaf experiment) demonstrate the particle nature of light?


What is the Schwarzschild radius of a black hole?


We're here to help

contact us iconContact usWhatsapp logoMessage us on Whatsapptelephone icon+44 (0) 203 773 6020
Facebook logoInstagram logoLinkedIn logo

© MyTutorWeb Ltd 2013–2024

Terms & Conditions|Privacy Policy
Cookie Preferences