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Physics: Post your doubts here!

Thought blocker

Thought blocker

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Kashaf Ali said:
View attachment 61484
could someone please do this....
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Ep = GMm/R
Change in Ep = GMm/change in R
That is Delta Ep = GMm*(1/R1 - 1/R2)
Thus coming to the question,
above earth surface is the TRICKY part of the question so the informatuon we have :
Earth radius : R
We have to find change in EP from R to 2R above earth surface now if u add earth surface R to this two Rs so
R1 = 2R and R2 = 3R

Use the formula ,
Delta Ep = GMm(1/2R - 1/3R)
Delta Ep = GMm/6R
 
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Aishayasin said:
Please can aNyone help me with part cii in detail as i am unable to solve these type of question
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These are the easiest ones.
A = Ao e^(-lambda x t) right?
We have to find A/Ao
Thus,
A/Ao = e^(-lambda x t)
we have lambda and t both given.
lambda = 0.025 years
and t = 5 years

Substitute this in the formula, and then answer will be 0.88 (2dp)
 
Frankuzi

Frankuzi

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I Believe said:
View attachment 61396
Why is the answer B?
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I think for this type of question playing around with conservation of linear momentum is the key:)
Let's consider a scenario where we first pour the sand into the cart, With the equation:
M(cart)*U(cart) = [M(cart) + M(sand)]*V
Rearranging the equation therefore we have:
V = [M(cart)*U(cart)]/[M(cart) + M(sand)] * U(cart)
This in return makes V less than U(cart) so the speed at X will decrease when being compared to its original state before adding the sand in.

Let us continue with the another scenario at Y,
similarly we will be using the conservation of linear momentum to solve for this,
When comparing scenario at X and Y,
[M(cart) + M(Sand)]*V =M(cart)*V ' (This is the case where the sand is dropped from the cart),
therefore making V ' the subject we have,
V' = [M(cart) + M(Sand)]*V/ [M(cart)]

Using the two underlined equation, simply play around with the equation by substituting the V,
Simplified and you will get V' = U which in the end the velocity remained unchanged as it was from the
beginning :D.

My way of approaching this type of question is usually in the sense of mathematical interpretation so there might be other way of explaining or visualizing this but feel free to correct or ask me if there is any problem with the explaination :D:)
 
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