All Answers 358087 Answers

its good Melody thats your here!i thought u wont be seen till Tuesday!

I think just the key stuff. I missed some lectures. I found the logic analysis of these questions difficult.

Two protons (p₁ and p₂) and an electron (e) lie on a straight line, as shown. The directions of the force of p₁on e, the force of p₂ on e, and the total force on e, respectively, are:

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And also,

The diagram shows a pair of highly charged plastic cubes that attract each other. 

Cube 3 is a conductor and is uncharged. Which of the following illustrates the forces between cubes1 and 3 and between cubes 2 and 3?

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They have been answered now but I guess with out calculating stuff (not that i'm sure I know where to begin) but would try. However, interpreting why they will move in such a way is what I'm not clear on. Just memorising it is not enough. Mostly I was after the key principles to help with my logic. Thanks. (btw I do get most of the basics but there's gaps.)

What is a moon well?

WOW!Aziz thats so totally different from my school!

All standards have 9 periods which can become 10 including the zero period!in my school on Wednesday the zero period is of an hour!

you im so surprised to see the education system , its all different from my school!We have no snack time but after the 5th period (not including the zero one) , we have out luch break , which i never counted was for how long but was enough to finish our luch and......the left time , the children play and most of them get a scolding becoz of playing and running in the classes and making the class no better than junk yard full of broken lying desks and chairs!lol!(but they dont break the things just scatter them about while running)

And after luch we have the left periods!we have our school of 6 hours!like going in am and returning in pm!lol!just a thought!The school is closed at 2pm and in the morning......i dont know exactly when it starts!

but if theres a substitution before or after the break then its a lot fun until the teacher is too serious about her duty becoz if theres a substitution then we all have nice chats and when the teacher says to read we just have our book open and then chat when the teacher is not looking!and those who have pending work they do their work and some read newspaper and u kow actually u can do anything u want until the teacher asks u to open the book and read it or disscusses about that subject!and if any teacher does this , u know what sounds are to be made by the students ..........................awwwwwe or ohhhh nooo!lol!

and you mean 194 watt not 192 ... right ? 

thanx 

what about the refractive  !! why the red is the least 

R=2000

n=4  (because 4 payments left)

i = 2% = 0.02

This is the present value of an ordinary annuity problem.

$$\boxed{A=R\times \frac{1-(1+i)^{-n}}{i}}\\\\
A=2000\times \frac{1-1.02^{-4}}{0.02}\\\\
A=\$7615.46$$

Now the bulb operated at 200 v and it power is 280

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No, it did not.

The bulb operates at 280W when a potential of 240V is its source.

When the voltage is lowered to 200v the energy used is lowered in proportion. In this case the bulb is using 192 watt-hours, not 280wh.

(Note error: The 192 watt-hours should be 194 watt-hours)

Resistance is hypothetically constant. It is determined using the rated standard operating conditions. The power is known and the voltage is known. Squaring the voltage then dividing by the power yields resistance. Dividing the (now) known resistance into the 200v source yields the current (in amps). If you then take the product of the amperage (0.97) and applied source voltage(200v) this yields the power (194 watts).

Remember the bulb only uses 280 watts when the voltage is 240V.

~~D~~

You know the initial amount and the end amount is 0

therefore it is a psesent value of an annuity question. It is an ordinary one because banks add the payments are made at the end of time periods (that is how banks work)

You haven't said how often the payments are made so I will assume yearly.

$$\boxed{A=R\times \frac{1-(1+i)^{-n}}{i}}$$

Actually on examination of the question it does not make a lot of sense.

I can work it out but it is not something you would ever bother with. Oh well not to worry.

n=5, A=1 200 000, n=5, i=0.24

You need to work out R which is your regular payment,

Mmm now it gets a bit obsure.

If you get that far maybe we can look at it together and work out what the question asker actually wants.  

You can work out total interest easily enough but each year a different amount of interest will be paid.

I can't understand it ! 

Now the bulb operated at 200 v and it power is 280 

so I can find the current by   I=P/V  ..... I=280/200 ... I = 1.4 A 

I want to understand my mistake in this way ! 

also in question 25 ! why the red ..؟ 

I'm based on this law  dsinx=mL      x :- is the angle   and  L :- is the wave length ! ? 

Looks like nine undecillion, four hunred sixty decillion, and eight nonillion.

This question makes no sense. Sorry.

 $$\\\mbox{You can expand this the long way but you should remember that}\\\\
\boxed{(a\pm b)^2=a^2\pm 2ab+b^2}\\\\

(3\sqrt{6}-5)^2\\
=(3\sqrt6)^2-[2*3\sqrt6*5]+5^2\\
=9*6-30\sqrt6+25\\
=54+25-30\sqrt6\\
=79-30\sqrt6\\$$

xvxvxv: In question number 1  why I can't use   P=V.I

You can, but you have to do it at the normal condition first: so 280=240*I_normal

I_normal = 280/240.

Ohms law says V = IR  so 240 = R*280/240 or R = 240²/280 

The resistance R, will be approximately the same at reduced voltage, so using Ohm's law again:

200 = I_reduced*240²/280

 I_reduced = 200*280/240²=0.972

(PS on question 16, go with thermal conductivity!).

In question number 1  why I can't use   P=V.I !! 

In fact, there is a way to get the calculator here to calculate this (using the npr function):

$${\frac{{\left({\frac{{\mathtt{365}}{!}}{({\mathtt{365}}{\mathtt{\,-\,}}\left({\mathtt{365}}{\mathtt{\,-\,}}{\mathtt{335}}\right)){!}}}\right)}}{{{\mathtt{365}}}^{{\mathtt{30}}}}} = {\mathtt{0.293\: \!683\: \!757\: \!280\: \!731\: \!3}}$$ 

I entered the above as npr(365,(365-335))/365^30.

The result isn't as small as you might expect:

Re. 16).  You might well be right David.  I just thought in terms of a relatively small block of metal/wood for which one might write  m.c_p.dT/dt = heff.A(T_hand - T) where heff is an effective heat transfer coefficient that would include thermal conductivity as well as a contact heat transfer coefficient.  In this case the heat transfer is likely to be dominated by c_p when it transfers to the right-hand side.

If we are talking about large blocks, with effectively infinite heat capacity, then it is probably better to write a similar equation from the hand's point of view, in which case it will probably be the contact resistance that dominates.

Never really thought about it much before - an interesting question to ponder!

Thanks Alan. The “mean-to-peak” for amplitude is helpful. (I was uncertain what applied to transverse waves).

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Interesting point on # 16.

I considered the specific heat aspect, but thought the psychometric formulas to have more weight here. Consider two substances that have a similar specific heat, but different conduction coefficients. Basically applying the same amount of heat will elevate each temperature the same amount. The rate at which these will absorb heat are different.

Though the total energy transferred for a given temperature rise is the same, the psychometric formulas would indicate a much colder “feel” by touch because the energy transfer is faster.

(I have never seen a collegiate physics test that didn’t have at least one question with ambiguity -- “The ubiquitous trick question.”)

~~D~~

In the last part of the last image it looks to me as though B) A and E is circled.  This is correct here, as amplitude is usually mean-to-peak.  Think of the curve as y = a*sin(x).  a is generally thought of as the amplitude and y varies from +a to -a.

NB David is correct about question1.  I missed that!

The bulb when operated at rated voltage of 240V uses 280W per hour. This indicates a resistance of

 E²/P (240²)/280W = 206 ohms.

Assuming a uniform resistance, the current (I) at 200V (E), with a resistance of 206 ohms equals * E/R =I -- - -> 200/206 = =0.972* The correct answer is 0.98 (b)

 Note: the actual resistance is slightly lower than the calculation. The electrical resistance nature of tungsten based filaments is non-liner, and produces a slightly lower resistance at lower temperatures. The lower resistance results in a higher current for the same voltage. This is probably why the answer indicates 0.98 instead of 0.97.

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For # 2 Your answer is correct.

From the Lorentz Force Law, for parallel motion in a magnetic field, the sine of the relative angle is zero.

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For # 12 Your answer is correct.

A= F/m * where, m = Mass, a = acceleration, and F= force

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For # 13 Your answer is correct.

The two temperatures scales converge at -40

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For # 16 Your answer is correct.

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For # 17 Your answer is correct.

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For # 18 Your answer is correct.

The value is very small: 8.17E-10 N

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 For # 19 Your answer is correct.

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For # 20 Your answer is correct.

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 For # 22- #24 Your answers are correct.

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 For # 25 The answer is (A). Red light is the least refracted.

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 For # 26 Your answer is correct

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 For # 29 Your answer is correct. (Though the magnitude is the same the vector is opposite).

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 For # 30 The answer is (A).

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The top part of the last image is indiscernible.

The lower portion.* For # 8. I am uncertain.

Transverse waves in matter are a displacement of the medium that is perpendicular to the direction of propagation of the wave.

Most graphs depict Amplitude in vertical format.

If this is the case here then the answer is (D) for D and E. For peak to peak amplitude.

If this is an exception to the standard (because of the waves nature) then (C) for A and C, is correct.

(Alan may be able to clarify this).

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~~D~~

The result of doing exactly what you specified is 1.069.

However, it looks to me as though you are trying to calculate the standard deviation of this data set, in which case you need to divide by 11 before taking the square root.  Also, the mean of the data (the value you are subtracting from each number) is 65.25 not 65.26.  If it is the standard deviation you really want then the result is 3.545.

If height, h = 20 - 16t² + 32t, then upward velocity, v = dh/dt = -32t + 32.  At its highest point the speed is zero, so this happens when -32t + 32 = 0 or when t = 1.  At this time the height is hmax = 20 -16*1² +32*1 = 36 feet

Most of them are, but:

16.  Metal feels colder than wood because the rate it draws heat from your hand is greater than that of wood.  Because it's the rate of transfer of energy that is important here, it is the specific heat capacity (larger for wood than metal, so rate of change of temperature is smaller) that matters most.

25. Red light is refracted least.

30.  Atoms radiate photons when they undergo a transition from a high energy state to a low one.

I can't read question 7 in the last image!

It is weird how the images are not showing; however, if you are on chrome and you right-click the image area and select "Inspect Element," you will see that after the link, there is something along the lines of alt = "x over..." or alt = "9 times x..." and these seem to fit the numbers found in the question.

Answer:

Part A: x mg/ 10 mg = number of pills given 

Part B: The total number of pills given over a period of 9 days

Part C: 30 pills - # pills given in 9 days = ? pills