I need some help understanding a problem regarding Friction Force.

AI Thread Summary
When standing on a skateboard and walking along its length, the skateboard moves in the opposite direction due to the backward force exerted by the person walking. This phenomenon is explained by Newton's third law of motion, where every action has an equal and opposite reaction. The static friction coefficient is sufficient to prevent slipping, allowing the skateboard to move backward instead of remaining stationary. The discussion also touches on the participant's intention to explore further physics questions after their exam. The conversation concludes with a sense of camaraderie and shared interest in physics.
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Homework Statement


This problem is regarding Friction Force:

Imagine a skateboard, low and with well-oiled bearings. What would happen if, standing over it at rest, you begin to walk along its length?

The Attempt at a Solution


There are 4 options. I chose this one:
It would start moving in the opposite direction.

The book says it's the correct Answer, but I'm not quite sure why that is.

Is it because the Static friction coefficient is bigger than the force I exert on the skateboard by walking?

P.D. Would it be against the rules if I post a new question, about the same topic in this same thread, once I get the last one answered?
 
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its not that its because action reaction.when you walk forward you exert a backward force on the skateboard which moves you forward and the backward force exerted by you moves the skateboard backward
 
Wow! Thanks, It seems a little more logical hehe :P

And it makes sense, since I'm studying Newton's 3 laws of motion. Thanks :)
 
welcome!if possible you can head for my question
 
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You mean this question: "CHALLENGING pHYSICS questions(dedicated for lover's of physics)" 'Cause if so, I'm totally trying to solve that one, right after my Physics exam on Friday (Today :D )

It seems interesting, mainly because I'll have to read some old stuff, as well as some new stuff to even attempt to solve it.

Bye! See you around :)
 
Kindly see the attached pdf. My attempt to solve it, is in it. I'm wondering if my solution is right. My idea is this: At any point of time, the ball may be assumed to be at an incline which is at an angle of θ(kindly see both the pics in the pdf file). The value of θ will continuously change and so will the value of friction. I'm not able to figure out, why my solution is wrong, if it is wrong .
TL;DR Summary: I came across this question from a Sri Lankan A-level textbook. Question - An ice cube with a length of 10 cm is immersed in water at 0 °C. An observer observes the ice cube from the water, and it seems to be 7.75 cm long. If the refractive index of water is 4/3, find the height of the ice cube immersed in the water. I could not understand how the apparent height of the ice cube in the water depends on the height of the ice cube immersed in the water. Does anyone have an...
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