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zip wire question

Different people have different speeds at the end of the zip wire. Explain why (2 marks)
Original post by HANGRY123
Different people have different speeds at the end of the zip wire. Explain why (2 marks)

I'm assuming a zip wire is inclined?
Before I begin with an explanation, what level of physics are you at? GCSE or AS/A Levels?
Different people have different masses and volumes

a larger person with the same weight will experience more air resistance and so will reach the bottom of the zipline at a slower speed
a heavier person with the same volume will have more inertia - and the force of air resistance will decelerate them less so they will reach the bottom of the zipline at a faster speed.


"a larger person has more potential energy, but they also have a larger mass to accelerate, so those two factors would cancel out. As small as air resistance and friction might seem, they are often significant when the only accelerating force comes from gravity (think soapbox derby racing). Air resistance is proportional to frontal area - roughly proportional to the square of a person's height, but mass depends on volume, which is roughly proportional to the cube of their height. So mass increases faster than air resistance, and heavier people will accelerate faster and travel further."

Source https://www.physicsforums.com/threads/why-do-heavier-people-go-further-on-a-zipline.913841/
Reply 3
Original post by qwert7890
I'm assuming a zip wire is inclined?
Before I begin with an explanation, what level of physics are you at? GCSE or AS/A Levels?

GCSE thanks
Reply 4
Original post by MTChemist
Different people have different masses and volumes

a larger person with the same weight will experience more air resistance and so will reach the bottom of the zipline at a slower speed
a heavier person with the same volume will have more inertia - and the force of air resistance will decelerate them less so they will reach the bottom of the zipline at a faster speed.


"a larger person has more potential energy, but they also have a larger mass to accelerate, so those two factors would cancel out. As small as air resistance and friction might seem, they are often significant when the only accelerating force comes from gravity (think soapbox derby racing). Air resistance is proportional to frontal area - roughly proportional to the square of a person's height, but mass depends on volume, which is roughly proportional to the cube of their height. So mass increases faster than air resistance, and heavier people will accelerate faster and travel further."

Source https://www.physicsforums.com/threads/why-do-heavier-people-go-further-on-a-zipline.913841/

Thanks :smile:
Reply 5
It will all be about air resistance and the weight to overcoming it. The surface area of the person affects air resistance and the persons weight the net force. Were the zip wire to be on the moon the people should reach the end at the same time
Reply 6
Original post by Zarek
It will all be about air resistance and the weight to overcoming it. The surface area of the person affects air resistance and the persons weight the net force. Were the zip wire to be on the moon the people should reach the end at the same time

Oh thanks this makes sense now! Could you help me with this pls? How would you work out the useful power output of an object using a straight line of a graph? :0
Reply 7
Original post by HANGRY123
Oh thanks this makes sense now! Could you help me with this pls? How would you work out the useful power output of an object using a straight line of a graph? :0


I have to think way too hard for that one
Original post by HANGRY123
Oh thanks this makes sense now! Could you help me with this pls? How would you work out the useful power output of an object using a straight line of a graph? :0

a straight line graph of..?

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