# Absolute and Relatiave Uncertainty (partial derivatives)

#### 3ephemeralwnd

1. The problem statement, all variables and given/known data

Calculate the following, expressing all results with uncertainties both in absolute and relative (percentage) form:

a) A + B

b) A x B

c) Asin(theta)

d) A^2 / Bcos(theta)

The relevant formula for the absolute uncertainty is below, but i have no idea how to use it! The teacher just sort of gave us the assignment without much explanation.. I know that it uses something called partial derivatives, could someone explain how to find that?

#### Attachments

• 1.5 KB Views: 160

#### rock.freak667

Homework Helper
Assuming you know how to take derivatives, a partial derivative is just holding all the other variables as constant.

So if we had z=xy and we wanted to get ∂z/∂x, we would hold 'y' constant and differentiate like normal to get ∂z/∂x = y.

For this exercise, you should at least know how to take derivatives.

### The Physics Forums Way

We Value Quality
• Topics based on mainstream science
• Proper English grammar and spelling
We Value Civility
• Positive and compassionate attitudes
• Patience while debating
We Value Productivity
• Disciplined to remain on-topic
• Recognition of own weaknesses
• Solo and co-op problem solving