# Physics Pendulum Question

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#1
So this is just something I was discussing with my boyfriend.

If you were abseiling and were hit with a 30mph gust of wind...
a) how far from the wall would you go
b) with what speed would you swing back towards the wall

Say the individual weighs 80kg and are 50m down the wall.

I have been trying to figure it out, but am not from a physics background so am struggling.
0
11 months ago
#2
(Original post by Em_allen)
So this is just something I was discussing with my boyfriend.

If you were abseiling and were hit with a 30mph gust of wind...
a) how far from the wall would you go
b) with what speed would you swing back towards the wall

Say the individual weighs 80kg and are 50m down the wall.

I have been trying to figure it out, but am not from a physics background so am struggling.
you'd have to make some assumptions about how hard the gust was able to push you initially.

treating this as a question about simple pendulums there are a couple of relevant things we can say...
you could calculate how much time it would take to get back to the wall if you know the length of rope above you because T=2ᴫ sqrt(L/g)
T is the time for a full cycle so you'd be back at your starting position on the wall in T/2 (the weight of the individual doesn't affect this time, just the length of the rope)

your speed when you arrived back at the wall would be the same as the speed you were initially pushed away from the wall
0
11 months ago
#3
I gave it a good go and referred to my smart friend and two teachers. It was an energy question. when the person gets pushed by the wind, I assumed a full transfer (all the wind hit him in one go and no energy was lost) meaning he also traveled at 13.4 m/s. I used the kinetic energy formula: (mv^2)/2 which then allowed me to find the GPE (gravitational potential energy)=mass x gravity x height(or in this case distance blown). grav=9.81, mass=80 rearrange gives me the distance blown. but this was boring so then I used trigonometry to find the altitude difference from the rest position and the distance along with a bit of circle stuff. I got a height difference of 0.57m. as for the speed, you swing back, that would just be the same he moved away with. take a bit due to drag of course. unless you assume a constant blow in which case, it gets a bit harder and I was not able to do. or attempt rather. I got bored and stopped at all the aforementioned info.
A lot of assumptions were made but you know. physics is like that. instead of an atmosphere, we have a vacuum. instead of a person, we have a perfectly smooth ball.
0
11 months ago
#4
Y did i pick physics?
its soooooooooooooooooooo hard
0
11 months ago
#5
(Original post by klopp)
y did i pick physics?
Its soooooooooooooooooooo hard
that's why i picked it
0
11 months ago
#6
(Original post by β0b)
that's why i picked it
I say that... but I avoided chemistry because it's hard.
0
11 months ago
#7
(Original post by Em_allen)
So this is just something I was discussing with my boyfriend.

If you were abseiling and were hit with a 30mph gust of wind...
a) how far from the wall would you go
b) with what speed would you swing back towards the wall

Say the individual weighs 80kg and are 50m down the wall.

I have been trying to figure it out, but am not from a physics background so am struggling.
Mass actually doesnt matter for pendulums. Also it depends how much wind it was (and how long it was in contact for) as well as its speed. Basically you need the force.
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