# Torque and the angle turned

1. Jul 16, 2007

### Mash

Ok, So if i calculate the torque on an object, how do i then find out the rate at which that object turns?

2. Jul 16, 2007

### Staff: Mentor

Given the torque (and the rotational inertia) you can calculate the angular acceleration. The rest is kinematics.

3. Jul 16, 2007

### Mash

Ok, so this is for a snowboarding game..

What would be an approximate rotational intertia for a snowboader? His mass in the game is 75kg's.

Or how would I go about working out what his rotational intertia would be? I guess it would depend on the position of your arms and things wouldn't it.

Could I just approximate the snowboarder to be a solid cylinder or something?

4. Jul 16, 2007

### olgranpappy

that sounds appropriate to me.

5. Jul 16, 2007

### GoldPheonix

hm..

Well, there's a list of equations in physics that explain rotational motion:

$$\Sigma\tau = I\alpha$$

Which allows you to relate torque to rotational acceleration. Then you can do the algebra to solve for, and calculus to integrate, the formula to get, in essence:

$$\Delta\theta = \omega t + 1/2[\Sigma\tau/I] t^2$$

But also, yes, it is reasonable to assume that the torque will distribute itself in a uniform way on the skier.

6. Jul 16, 2007

### rcgldr

The way a snowboarder turns is complicated. A person can twist his body at the waist causing the snowboard to yaw (a similar method is used for unicycles). A person can shift weight on the board front to back and also inwards and outwards with the twist at the waist method to create a lean. A person can also just hop and yaw the snowboard. Leaning on the edges of the snowboard will cause it to turn.