Physics

[Zenyth 6,494]

Okay, I got a question for you physics buffs. People in tenth grade and above need not scoff at this question, nor need any of you google this question:

 

A block hangs from a spring balance, and the latter reads 20 N. A bucket full of water is weighed on a weighing machine, and the weighing machine reads 40 N. Now, the block is completely immersed in the water (STILL attached to the spring balance). Find the new reading on the weighing machine.

 

NB - As the experiment is being conducted, the bucket remains on the weighing machine.

 

It's very, very, VERY easy - you just need to get your concepts clear.

You didn't specify the reading of spring balance after immersing block in water..

[TriNitroToIuene 4,765]

You didn't specify the reading of spring balance after immersing block in water..

Oh, damn, I'm so sorry, the spring balance reads 16 N.

[Quarks 2,255]

It's actually for 9th grade, I actually implied that 10th graders will find this easy :lol:

That is your school system, I am in 10th grade, and we do physics 11th grade(junior year), so I inherently do not know everything here, which is sad, as I enjoy physics, and for a quantum physics question, can a singularity destroy the universe as we know it?

[beaku 2,656]

That is your school system, I am in 10th grade, and we do physics 11th grade(junior year), so I inherently do not know everything here, which is sad, as I enjoy physics, and for a quantum physics question, can a singularity destroy the universe as we know it?

Trillions of singularities already exist. And we're alive, right?

[Quarks 2,255]

Trillions of singularities already exist. And we're alive, right?

But none are large enough at this moment, if a singularity is large enough, could it not alter or destroy the fabric of space and time? Also, many of the trillions of singularities that you have mentioned have not reached their maximum size. I will leave you to ponder this.

[hhgb 2,655]

I hope you understand this.

[beaku 2,656]

But none are large enough at this moment, if a singularity is large enough, could it not alter or destroy the fabric of space and time? Also, many of the trillions of singularities that you have mentioned have not reached their maximum size. I will leave you to ponder this.

OMG! You've got it all wrong. First of all, Universe's Censorship law doesn't allow naked singularities to exist. They will always be covered with Event Horizon. All of them evaporate at some point of time, thanks to Hawking Radiation. It's totally impossible for any kind of singularity to destroy a galaxy, let alone universe.

[Zenyth 6,494]

tan(a) =k

Where 'a' is angle of slope. -_-

You didn't prove it..

Component of weight mgsin(a) is balanced by frictional force kmgcos(a) where mgcos(a) is normal reaction on block. Equatig these two and dividing gives us angle of repose tan(a)=k.

[beaku 2,656]

You didn't prove it..

Component of weight mgsin(a) is balanced by frictional force kmgcos(a) where mgcos(a) is normal reaction on block. Equatig these two and dividing gives us angle of repose tan(a)=k.

Didn't I get the same answer? You don't have to prove such obvious equations!

[Penguin40 1,714]

Okay, I got a question for you physics buffs. People in tenth grade and above need not scoff at this question, nor need any of you google this question:

 

A block hangs from a spring balance, and the latter reads 20 N. A bucket full of water is weighed on a weighing machine, and the weighing machine reads 40 N. Now, the block is completely immersed in the water (STILL attached to the spring balance) and the spring balance now reads 16 N. Find the new reading on the weighing machine.

 

NB - As the experiment is being conducted, the bucket remains on the weighing machine.

 

It's very, very, VERY easy - you just need to get your concepts clear.

Ok, I surrender cause I don't know that much (I know you all will laugh, but I'm still in junior school.). But I'll guess. Somewhere around 30 N?

 

And a question for all of you, really simple: What is total internal reflection? Please explain. 

[TriNitroToIuene 4,765]

Ok, I surrender cause I don't know that much (I know you all will laugh, but I'm still in junior school.). But I'll guess. Somewhere around 30 N?

It's actually 44N, but nice try anyway :)

[Darren4Turbo 4,913]

I'll study physics next year in school when I'll be in grade 7. I don't know what is even physics.

[Penguin40 1,714]

It's actually 44N, but nice try anyway :)

Oh, btw I like physics, so can you teach me how 44N?  :lol:  :)

[beaku 2,656]

20-4 = 16

40+4 = 44

[Zenyth 6,494]

Oh, damn, I'm so sorry, the spring balance reads 16 N.

So buoyancy force on block is 4N. Normal reaction = reading of weighing machine = 44N.

I'm not totally sure whether my explanation is spot-on though.

Edited October 26, 2015 by Zenyth

[Zenyth 6,494]

Didn't I get the same answer? You don't have to prove such obvious equations!

But I said prove it in the Q itself and it isn't obvious to eveyone here.

 

Anyway my next Q for you all.

Q: In a Young's Double Slit Experiment light from the two coherent sources is of 6000 Angstrom wavelength and path difference registered is 0.0075 mm at a point X on screen then find number of bright and dark bands from he central maxima upto point X excluding the central maxima.

[TriNitroToIuene 4,765]

Oh, btw I like physics, so can you teach me how 44N?  :lol:  :)

Okay, so we calculated buoyant force as 20-16 = 4 N.

 

But, the block exerts an equal and opposite force (Newton's 3rd law) on the water in the downward direction, hence making the force downwards 20N (it's weight) + 4N = 24N. However, a buoyant force of 4N and the tension force of the string (16N) act upwards so that makes the force upwards as 4N + 16N = 20N.

 

Since they are in the opposite directions, you can subtract the forces to get the 'net' force, ie sum of the forces in all directions, and you will get it as 4N downwards (24N downwards - 20N upwards). This 4N will add to the existing 40N weight of the bucket of water, thus making the reading on the weighing machine 40N + 4N = 44N.

[Penguin40 1,714]

20-4 = 16

40+4 = 44

Heheh, simple maths. 

[beaku 2,656]

But I said prove it in the Q itself and it isn't obvious to eveyone here.

 

Anyway my next Q for you all.

Q: In a Young's Double Slit Experiment light from the two coherent sources is of 6000 Angstrom wavelength and path difference registered is 0.0075 mm at a point X on screen then find number of bright and dark bands from he central maxima upto point X excluding the central maxima.

Stop asking formula based questions. It just doesn't add to anyone's knowledge. Also, I hate optics. -_-

[Penguin40 1,714]

Okay, so we calculated buoyant force as 20-16 = 4 N.

 

But, the block exerts an equal and opposite force (Newton's 3rd law) on the water in the downward direction, hence making the force downwards 20N (it's weight) + 4N = 24N. However, a buoyant force of 4N and the tension force of the string (16N) act upwards so that makes the force upwards as 4N + 16N = 20N.

 

Since they are in the opposite directions, you can subtract the forces to get the 'net' force, ie sum of the forces in all directions, and you will get it as 4N downwards (24N downwards - 20N upwards). This 4N will add to the existing 40N weight of the bucket of water, thus making the reading on the weighing machine 40N + 4N = 44N.

Thanks.  :)

[m6ttetu 288]

Just ended to study physics and don't want it here too  :unsure:

[personia 4,036]

Yay for physics!

[hhgb 2,655]

I hope you understand this.

:lol: