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## Class 11 Physics (India)

### Course: Class 11 Physics (India)>Unit 9

Lesson 9: Friction

# Correction to force of friction keeping the block stationary

The video corrects a calculation error from a previous lesson on determining the coefficient of static friction. The instructor recalculates the coefficient using the correct values, resulting in a coefficient of static friction of 0.59. Created by Sal Khan.

## Video transcript

Just realized that I typed in the wrong numbers at the end of the last video when I was trying to put them in the calculator. We were trying to determine the coefficient of static friction, and it's 50 newtons divided by 49 square roots of 3 newtons. And in the last video, by accident, in the calculator, instead of doing 49 square roots of 3, I wrote 40 square roots of 3. So let's actually calculate it again. 50 divided by 49 times-- let me write it this way, make sure we get-- 49 times the square root of 3 gives us a coefficient of static friction of, if we round it, 0.59. So this is equal to 0.59. And so that's it. I just forgot to-- I did the calculation wrong on the calculator in the last video.