# Why are the variables different in Hibbeler's Dynamics?

1. Nov 13, 2015

### chval

I am currently in a college dynamics class, and we are discussing energy and work. In other classes(calculus or physics), we have represented work, potential energy, and kinetic energy with the variables W, K, and U (respectively). However, in my dynamics book, these are represented using the variables U, V, and T (again respectively). Does anyone know the origin of these notation differences? The FE reference handbook also uses the second set, so I assume it is an engineering-only decision. Wikipedia also recognizes that kinetic energy may be used with K, T, and EK and potential with U, V, and EP but doesn't mention using U with work.

I'm extra curious because the differences are confusing some of the other students who can't see work as both U and W, and I'd love to have an explanation to help them understand better. Any help would be very appreciated!

2. Nov 13, 2015

### Student100

I would assume there is no other reasoning then someone liked those letters/it made sense to someone who wrote the text. It's like the differences in ${\rm I\!R}^3$ for the standard basis vectors in physics texts, $\hat{i},\hat{j}, \hat{k}$ or the more logical (to me) $\hat{x},\hat{y},\hat{z}$.

There could be a good explanation though.