# Free Body Diagrams for hockey puck

1. Oct 1, 2009

### Chandasouk

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

A hockey puck slides along a horizontal, smooth icy surface at a constant velocity as shown. (Part A figure) Which of the following forces act on the puck?

Okay, for this the choices are (list check all that apply)

force of velocity x
air drag
weight x
acceleration
force of push x
normal force x
friction

Since it is on an icy surface, I neglect friction and I ignored air drag because in the introduction, it told me

the force of air drag, similar in some ways to the force of friction, may come into play. These forces are directed so that they resist the relative motion of the surfaces. To simplify problems you often assume that friction is negligible on smooth surfaces and can be ignored. In addition, the word friction commonly refers to resistive forces other than air drag that are caused by contact between surfaces, so you can ignore air drag in problems unless you are explicitly told to consider its effects.

I was wondering why my choices were not correct?

2. Oct 2, 2009

### tiny-tim

Hi Chandasouk!

i] velocity has no force (were you thinking of momentum? momentum isn't a force)

ii] it's sliding, so why do you think anything is pushing it?