## Monday, February 1, 2010

### The Physics of Rollerblading and Friction

Have you ever wondered…what caused a person wearing rollerblades to start forward when they are at rest or how does the friction occur between the skates and the ground??? Well in order for the in-line skater to begin moving, he or she must experience a force in the direction of motion which causes her to accelerate from rest to some velocity. An inline skater at rest is only exerting a force down upon the ground (gravity) and the ground is exerting an opposite but equal force up on the skater. All four wheels of the rollerblade are in contact with the surface. The wheels begin to rotate due to the frictional force (static friction) between the wheels and the surface. The static friction exerts torques on the wheels which makes them spin. In order to eliminate any sliding friction, the rollerblade wheels rotate using a ball bearing system. To get a full grasp on the friction and rollerblading click on the link below.

1. Great idea. Some suggestions:
http://ta8ter30.glogster.com/friction-and-fun/

- You quote acceleration (use a small not caps) as 10 m/s^2 but then you used 9.8 m/s^2
- One answer has no units!

2. Awesome job Taylor!
I really like how you added music in.
I'm finding your glogster really hard to read though - I think it's the background comined with the small text...
Also, in the box with the physics equations I think you switched your Fx and Fy. Fy should be Fn = Fg and Fx should be Ft - Ff = ma.
Looks good!

3. Taylor! The story on glogster was so cute but I have to agree with Sydney, it was very hard to read with the background being so bright and busy. Other than that everything looked pretty good! Just maybe work on the fonts etc.

5. This comment has been removed by the author.

6. Ive updated by gloster please have a look

7. Taylor, it is not clear what mass are you referring too. 15 kg is just about 33 lbs!
Also you are asking for mu but you only calculated a friction 46.94 with no units.
Please clarify what the objective of your example is and be sure that everything is corrected as I will grade it tomorrow!

8. Ok i think i fixed everything correctly!!

9. A person can not be 150N. You put, "If person A is 150N and is being..."

I think you meant the force of gravity acting on it. The mg which you said equals 150N. So just a wording problem.

10. Well, now that I think about it, I guess you could say a person is 150N, but I think it would be more clear if you said maybe weighs 150N? But good job overall. I like what you did with the pictures and videos.

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