Rearranging Equations
Lots of equations in Physics are three term equations and these can be put into formula triangles.
To use a formula triangle you cover the value you want with your hand and look at the other two.
If the two are side by side you multiply them. If one is above the other and it looks like a fraction, you divide it by the other. Try it for this formula triangle. |
Distance = Speed x Time
Speed = Distance / Time Time = Distance / Speed |
If you don't like formula triangles, you need to think about things a little more mathematically.
If you want to move things from one side of the equals sign to the other, you need to do the opposite to what it is doing.
For example, if we take,
Distance = Speed x Time
And we want to find out what speed is: speed is currently being multiplied by time so we want it to move to the other side, this means the it needs to be dividing, giving us:
Distance / Time = Speed
Now, if you wanted to rearrange it to find time: time is currently on the bottom of a fraction and we want it on the top, so we have to multiply by it. This will move it to multiplying speed.
Distance = Time x Speed
Now we need to divide by speed to get time on its own.
Time = Distance / Speed
It is the same with adding, if it is positive on one side of the '=', it will become negative on the other.
If you want to move things from one side of the equals sign to the other, you need to do the opposite to what it is doing.
For example, if we take,
Distance = Speed x Time
And we want to find out what speed is: speed is currently being multiplied by time so we want it to move to the other side, this means the it needs to be dividing, giving us:
Distance / Time = Speed
Now, if you wanted to rearrange it to find time: time is currently on the bottom of a fraction and we want it on the top, so we have to multiply by it. This will move it to multiplying speed.
Distance = Time x Speed
Now we need to divide by speed to get time on its own.
Time = Distance / Speed
It is the same with adding, if it is positive on one side of the '=', it will become negative on the other.