diff --git a/02_lois_de_newton.md b/02_lois_de_newton.md
index d366d096f9baf0f530040bc935ba03a0592a5534..818822a297382aa4cc3056c4f899f8eeac16e734 100644
--- a/02_lois_de_newton.md
+++ b/02_lois_de_newton.md
@@ -1104,7 +1104,7 @@ Solution (La balle qui tourne) #
 
 Nous savons que la balle subit une force 
 $$
-F\mathrm{res}=m a_R=m \frac{v^2}{r}=m\frac{(2\pi r)^2}{T}\frac{1}{r}=\frac{4\pi^2 r}{T}=\frac{4\pi^2}{10}\cong 3.95\N.
+F\mathrm{res}=m a_R=m \frac{v^2}{r}=m\frac{(2\pi r)^2}{T^2}\frac{1}{r}=\frac{4\pi^2 r}{T^2}=\frac{4\pi^2}{100}\cong 0.395\N.
 $$
 
 ---