Is it just translational motion or also rotational?

In summary, the net rotational motion of a person walking up a hill is due to the increased separation of blood vessels near the summit.
  • #1
boris16
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0
In translational motion all parts of rigid body move with same speed and in same direction!I have a bit of problem between figuring out if particular motion is just translational or also rotational.

If person slowly walks on top of gently rising hill, is his motion also at least partially rotational? If yes, why so? If not, why not ?

Is any motion the path of which is (even if just a little bit) curved also rotational, or just rotational ?

bye
 
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  • #2
If you graph the instantaneous motion of each body part as a function of time while climbing the hill, there will be a mix of translational and rotational motion. The net by the time you get to the top of the hill will almost 100% translational, and the net average of all the rotational motion will be very close to zero. Now if we had tank treads instead of legs to generate our motion, then there would be a net rotational motion in climbing the hill, right?
 
  • #3
Why will it also be rotational?
 
  • #4
Look at how the legs move for each step. Thigh bone rotates up, shin bone rotates forward, thigh bone rotates down, etc.

Doh! I just thought of a rotational component that will not average to zero for the person walking up the hill (or swimming or sitting still driving...). Can you think of what it is?
 
  • #5
berkeman said:
Look at how the legs move for each step. Thigh bone rotates up, shin bone rotates forward, thigh bone rotates down, etc.

Doh! I just thought of a rotational component that will not average to zero for the person walking up the hill (or swimming or sitting still driving...). Can you think of what it is?

I'd say peni* or boobs if there is no bra and they big enough to jiggle?o:)
 
  • #6
LOL. Nope, those body parts don't rotate in a net way. Hint -- what I'm thinking of is rotating in your body even if you are sitting still.
 
  • #7
I have no idea,but I thought of something:

I thought if there was a curve,no matter how small ( I don't mean small in a sense that you can step over it ) there is some rotation going on or perhaps even just rotation without translational movement? If there would be no friction and you'd be dragging up the hill(with small curve) a small box,would then perhaps movement be just rotational or... ?

in any case,thanx for helping
 
  • #8
boris16 said:
I have no idea
I was thinking of blood circulation. Blood doesn't exactly circulate "around" the volume of the body, because arteries and veins are largely intertwined. But there are a few places where the separation is enough to give a net angular momentum to the blood flow in the body. And that angular momentum increases when you walk uphill...moreso for some than others! :rofl:
 

1. What is the difference between translational and rotational motion?

Translational motion refers to the movement of an object in a straight line, while rotational motion refers to the movement of an object around an axis or point. In translational motion, the entire object moves together, while in rotational motion, different points on the object have different speeds and directions of movement.

2. Can an object have both translational and rotational motion at the same time?

Yes, an object can have both translational and rotational motion at the same time. For example, a spinning top has both rotational motion around its axis and translational motion as it moves across a surface.

3. What causes rotational motion?

The main cause of rotational motion is torque, which is a force that causes an object to rotate around an axis. This torque can be applied by external forces, such as a person pushing a door to open it, or by internal forces, such as the gravitational pull between the Earth and the Moon causing the Moon to orbit around the Earth.

4. Is it possible for an object to have only rotational motion and no translational motion?

Yes, it is possible for an object to have only rotational motion and no translational motion. This can occur when the axis of rotation is fixed and the object is not moving or changing position in space. An example of this is a spinning top spinning on a stationary surface.

5. How does rotational motion affect an object's inertia?

Rotational motion affects an object's inertia differently than translational motion. In translational motion, an object's inertia is directly related to its mass, but in rotational motion, an object's inertia is affected by both its mass and its distribution of mass around the axis of rotation. This means that objects with the same mass can have different rotational inertia depending on how their mass is distributed.

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