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.
LM
Related Physics A Level answers
All answers ▸The friction coefficient of Formula 1 car tyres are around 1.7 in dry weather. Assuming sufficient power from the engine, calculate the theoretical best 0-100 km/h acceleration time in seconds. (neglect downforce, g=9.81m/s^2)
The speed of water moving through a turbine is 2.5 m/s. Show that the mass of water passing through an area of 500 metres squared in one second is about 1 x 10^6 kg (density of sea water = 1030 kg/m^3)
A rocket travels with constant velocity in a straight line in deep space. A ball is thrown from the back to the front (ie from the thrusters to the nose). Describe the path of the ball. Describe the path if the rocket were accelerating along this line.
An electron is emitted from a cathode in an electron gun, with a potential difference of 150kV. Find the velocity of the electron after it is accelerated and find the De Broglie wavelength.