Video Transcript
Albert Einstein’s famous formula 𝐸 equals 𝑚𝑐 squared, where 𝑐 is the speed of light, relates the energy, 𝐸, contained in matter and its mass, 𝑚. Rearrange the formula to make 𝑐 the subject.
In order to rearrange or change the subject of a formula, we need to use our knowledge of inverse operations and the balancing method. In this question, as we want to make 𝑐 the subject, we need to get this letter on its own on one side of the equation. We begin by dividing both sides of the equation 𝐸 equals 𝑚𝑐 squared by 𝑚. The left-hand side becomes 𝐸 divided by 𝑚. And the right-hand side becomes 𝑐 squared as the 𝑚’s cancel.
The inverse or opposite of squaring is square rooting, so we need to square root both sides of this equation. On the left-hand side, we have the square root of 𝐸 over or divided by 𝑚. The square root of 𝑐 squared is equal to 𝑐.
Rearranging the formula 𝐸 equals 𝑚𝑐 squared to make 𝑐 the subject gives us 𝑐 is equal to the square root of 𝐸 over 𝑚.
