Hot Air Balloon Ride!

Introduction

Krishna and Sharky are out on a Hot-Air Balloon ride, and to their horrors, the balloon, instead of moving up with a speed of 27.949783 27.949783 kmph, was moving down with the same. To make it move up with that speed, they need to reduce the weight.

Problem

The Hot Air Balloon has hot air filled in it, which gives it a constant upward force of 1000 1000 Newtons and an air resistance, always working against the direction of velocity and directly proportional to the speed, acts on the Balloon. They want to reduce the weight, and Krishna suggests throwing their clothes off, which Sharky aggressively rejects with a bright idea.

'Let's Vomit!' yells Sharky to Krishna, 'It's the easiest and the safest way to reduce mass on the Balloon.' Krishna reluctantly agrees.

It so happens that Krishna drank a lot of water before coming, and so his vomit is dilute with a density of 7.7 7.7 g/cc. And Sharky ate a wild bird in the morning, so the density of his vomit is 10 10 g/cc.

Krishna and Sharky weigh 62.7 62.7 and 52 52 Kilograms respectively. They need to vomit so that their Balloon starts going up with the same velocity.

How many millilitres does Krishna vomit, given that Sharky vomits 2.5 2.5 Litres.

Assumptions

The value of g g should be taken as 10 m / s 2 10m/s^2 and the Balloon has negligible mass. Any other assumptions which seem understood can be taken.

Extra Details

All the facts which appeared in this problem are correct. It was a tough task to find the densities of vomits of Krishna and Sharky.


The answer is 571.4.

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2 solutions

Joshua Daniel
Nov 28, 2014

Force downward = (62.7+52)*10 = 1147 N & force upward = 1000 N

From the given information, we see theres a net force of -147 N on the balloon (minus sign implies direction). But if the balloon is to maintain constant velocity the net force should be 0. From this we can infer that the air resistance must be equal to +147 N @ -28 m/s & -147 N @ 28 m/s

Now since we want the balloon to go upwards at the speed 28 m/s, total force downwards needs to equal 1000N - 147N (the air resistance at 28m/s)= 853 N

Therefore we need to remove some weight form the balloon, which is partly achieved with sharky vomitting out 2.5*10 = 25 kilograms or 250N

so

  1147-250-x = 853 N

   x = 44N or 4.4kg

This means Krishna will have to vomit 4.4/7.7 = 0.5714 L = 571.4 ml

Nice solution, i like the part where you said "This means Krishna will have to vomit 4.4/7.7 = 0.5714 L = 571.4 ml" xd @Satvik Golechha and @Krishna Ar

Mardokay Mosazghi - 6 years, 6 months ago

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Yeah! This is cinched to be the most bizarre Brilliant has ever had!! Be prepared to vomit, @Krishna Ar .

Satvik Golechha - 6 years, 6 months ago

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ha ha nice problem man, i coudnot tag people though

Mardokay Mosazghi - 6 years, 6 months ago

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@Mardokay Mosazghi Yeah, dunno why. I tagged them for you, BTW.

Satvik Golechha - 6 years, 6 months ago
Gautam Sharma
Nov 28, 2014

Let the force due to air resistance is

k v ( v ^ ) kv(-\hat { v } )

Now as in first case v is downward So force due to gravity is greater than upward force by Hot-Air Balloon. As it is moving with constant speed F n e t { F }_{ net } =0

(M is total mass of krishna and sharky=114.7)

M g 1000 k v = 0 Mg-1000-kv=0

now in second case Hot-Air Balloon is moving with constant speed upwards.

(m is their reduced mass after the vomit)

1000 m g k v = 0 1000-mg-kv=0

We get m=85.3kg

Mass lost due to vomit = 114.7-85.3=29.4kg

Now conservation of mass,

Let V be Volume of Diluted vomit due to drinking a lot of water by Krishna

29.4 = ( 10 k g / l 2.5 l ) + ( 7.7 k g / l V l ) 29.4=(10kg/l*2.5l)+(7.7kg/l*Vl)

We get V=571.4ml.

Are they still in air or they ate some birds in air and got down.LOL.just kidding.

LOL That is still a mystery. Maybe I'd let the cat outta the bag in the sequel.

Satvik Golechha - 6 years, 6 months ago

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waiting for it .

Gautam Sharma - 6 years, 6 months ago

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"EXTRA DETAILS All the facts which appeared in this problem are correct. It was a tough task to find the densities of vomits of Krishna and Sharky."

Just cant stop laughing.

Gautam Sharma - 6 years, 4 months ago

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