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I have my Physics exam tomorrow and I have a few questions in various chapters.

Measurements and uncertainties:

If in a calculation, I find the answer to be 500, but the numbers that I used all have 3 significant figures, would I be able to give the answer as 500? Does that have 3 significant figures? Or would the answer be 5 x 102 ?

When finding the absolute uncertainty with the percentage or maximum/minimum method, what are some rules that apply here? In my notes I wrote down that if there is addition or subtraction in the original equation, then I must add the absolute uncertainties. But when there is multiplication, division or indices, then I must add the percentage uncertainties. Is this correct?

Kinematics:

I'm really confused about a question in a Paper 1. 

"A constant horizontal force FA is applied to a block m1. Block m1 is in contact with a separate block m2. The blocks remain in contact as they accelerate along a horizontal frictionless surface. m1 has a greater mass than m2. Air resistance is negligible. Which statement is correct?"

1034555953_ScreenShot2018-06-03at18_39_18.png.23091af0902c184a61ffce7927dae71c.png

So I picked D which was "The force that m1 exerts on m2 is equal to F", but I was wrong and the actual answer was B "The force that m1 exerts on m2 is less than F". Why is that?

Thermal physics:

I would appreciate any common examples/questions involving the method of mixtures, since I haven't succeeded in solving one yet. By method of mixtures, I mean mcΔθ = mLf + mcΔθ. Would this equation work in every situation or should I be careful? 

Circular motion and gravitation:

For g = F/m, if you have a satellite orbiting a planet, is 'm' the mass of the satellite or the planet?

For tanθ = v2/Rg, what does 'R' represent? Is it the normal force or the molar gas constant?

Also, when you write ' -g', does that equal -9.81 ms-2 or +9.81 ms-2 ?

General:

Does uppercase P stand for power and lowercase p stand for pressure?

Also, how should I approach ratio questions?? I sometimes get them right but sometimes not. What should I start with? 

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1 hour ago, Allemande135 said:

I have my Physics exam tomorrow and I have a few questions in various chapters.

Measurements and uncertainties:

If in a calculation, I find the answer to be 500, but the numbers that I used all have 3 significant figures, would I be able to give the answer as 500? Does that have 3 significant figures? Or would the answer be 5 x 102 ?

When finding the absolute uncertainty with the percentage or maximum/minimum method, what are some rules that apply here? In my notes I wrote down that if there is addition or subtraction in the original equation, then I must add the absolute uncertainties. But when there is multiplication, division or indices, then I must add the percentage uncertainties. Is this correct?

Kinematics:

I'm really confused about a question in a Paper 1. 

"A constant horizontal force FA is applied to a block m1. Block m1 is in contact with a separate block m2. The blocks remain in contact as they accelerate along a horizontal frictionless surface. m1 has a greater mass than m2. Air resistance is negligible. Which statement is correct?"

1034555953_ScreenShot2018-06-03at18_39_18.png.23091af0902c184a61ffce7927dae71c.png

So I picked D which was "The force that m1 exerts on m2 is equal to F", but I was wrong and the actual answer was B "The force that m1 exerts on m2 is less than F". Why is that?

Thermal physics:

I would appreciate any common examples/questions involving the method of mixtures, since I haven't succeeded in solving one yet. By method of mixtures, I mean mcΔθ = mLf + mcΔθ. Would this equation work in every situation or should I be careful? 

Circular motion and gravitation:

For g = F/m, if you have a satellite orbiting a planet, is 'm' the mass of the satellite or the planet?

For tanθ = v2/Rg, what does 'R' represent? Is it the normal force or the molar gas constant?

Also, when you write ' -g', does that equal -9.81 ms-2 or +9.81 ms-2 ?

General:

Does uppercase P stand for power and lowercase p stand for pressure?

Also, how should I approach ratio questions?? I sometimes get them right but sometimes not. What should I start with? 

Indeed you add % uncertainties in multiplication or division.

For gravitation with satellites and planets you need the Coulomb Force law application for gravitationalforce -- you can look up gravitational force equation and it should give you. 

R represents the radius AKA the distance between the center and the rotating object... in no way is the molar gas constant related at all to those topics...

The sign of 'g' is related to how you're setting your reference points and depends on whether you're dealing with scalars or vectors.

Uppercase P typically represents Power but lowercase p does not always denote pressure. 

For approaching ratio questions, you should master general algebra, roots and squares, and know how to work with physics equations.

I'm going to be candid here -- you seem to be lacking an immense amount of understanding. If all those topics will be covered in the exam, then I'm sorry to say that you're extremely underprepared and one night's worth of cramming will solve little. 

What you need to start off with is understanding the basic principles and laws governing each of those toics before moving into specific scenarios. For example tan(theta) = V^2/Rg is a specific derivation of circular force for a particular situation, which is in itself a derivation of Newton's 2nd law. Also looking at your thermal physics equation you can see it's impossible for the equation to hold consider both of the same species are on both sides of the equation -- it would only work if Lf = 0 or m = 0 which is extremely unrealistic.

The key to doing well in Physics is indeed a lot of practice, but even before that you need to gain at least some background understanding in the concepts which can be achieved by reading the textbook or watching youtube videos (Khan Academy and Boseman Physics are great for these).

Good luck.

 

 

 

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500 does not have 3 significant figures; it only has 1. However, 500. (with the decimal point) would have 3 sig figs. 5.00 x 10^2 would be a better answer, because it makes it clearer that the number has 3 sig figs. I can't really answer the rest as I'm not starting IB yet, but I wish you all the best for your physics exam! You can do it! :D

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Measurements and Uncertainties When you answer questions on actual IB exams, you are permitted to have either one extra sig fig or one less sig fig. The exception is obviously when it is a sig fig question. That being said, "500" has 1 sig fig but "500." is generally accepted to have 3 sig figs because of the decimal point. 5.00 × 102 is also fine for 3 sig figs, but not always necessary on exams. You are correct on the error propagation.

Kinematics Assume the force that m1 exerts on m2 is M. The horizontal force on m2 is M to the right. By Newton's Third Law, the horizontal forces on m1 are F to the right, M to the left. Since m2 must have a net acceleration to the right, F > M.

Thermal physics Is θ temperature? I have seen T mostly, θ only in certain contexts. If so, the meaning of this equation is that the heat gained (or lost) by one substance due to temperature change, is equal to the heat lost (or gained) through vaporization and temperature change. Therefore, the equation is only valid when exactly one of the species undergoes a phase change. There is usually a minus sign across one the side, i.e. m1c1Δθ1 = -(m2L2 + m2c2Δθ2) to preserve the definition of Δ as final minus initial. 

Circular motion and gravitation 
i) g = F/m The g applies to the same object as m. For example if you want acceleration of Moon due to force from Earth, it is (force between Earth and Moon) / (mass of Moon).
ii) tanθ = v2/(Rg), R is radius of the bank or ramp.
iii) -g. The answer depends on whether g is a scalar or vector. When g is a scalar, -g is -9.81. When g is a vector, -g means a vector equal in magnitude but opposite in direction as the vector g. If down is positive, then -g is -9.81; if up is positive, then -g is 9.81. Typically if you have defined a positive vertical direction, g is a vector. 

General In the equations you may have encountered in year one, p is pressure and P is power. If you learned about momentum, p is also momentum. p and P may have additional meanings when you get to the Options. 

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