Why do attractive force have a negative sign? The book says its because one must be moving toward the other. But how does it make it negative? I dont understand. Can anyone explain the law of gravitation formula?? F= -GMm/r^2
Homework Statement
The mean diameters of Mars and Earth are 6.9 10^3 km and 1.3 10^4 km, respectively.?
The mass of Mars is 0.11 times Earth's mass.
(a) What is the ratio of the mean density of Mars to that of Earth?
(b) What is the value of the gravitational acceleration on Mars...
(Before I start, due to the use of vectors let me state I consider up to be positive and down to be negative)
Imagine a scenario, of a man in an elevator. And the elevator is accelerating upwards. Now in this case the Normal force > weight. So Normal Force - Weight =mass X acceleration. If...
I was wondering, if I were to drive in a flat road , and then on a banked road(steep), in a circular motion, which one would be more difficult to manoeuvre over. I thought of generalising the two, but obviously it won't work because in the flat road, it is the frictional force that acts as the...
Homework Statement
A clock is showing 3.30. Calculate the angular displacement in degrees from the 12.00 position of the clock to:
i the minute hand
ii the hour hand
I got my minute answer as 180 degree, which is right. But my second answer was 90 degrees, which apparently is wrong! the...
This topic is to do with circular motion..angular velocity. I have just begun this chapter in my a2 physics, and I don't really understand why the tip moves faster than the one near the centre. I understand it through calculations(using the different length of radius and then ω/angular...
Hey I am currently in the 12th Standard and want to, become a neuroscientist as well as a writer, however until recently I was thinking about writing later in life(like in my 50s). But recently I have come across various people advising me of the low pay of a neuroscientist, and also with the...
Can anyone tell me the relationship between work done and potential difference??
CAN ANYONE TELL ME THE RELATIONSHIP BETWEEN WORK DONE AND POTENTIAL DIFFERENCE??
If more work is being done across a component(for ex due to increased resistance), does the pd across it increase or decrease? I...
WHat is the uncertainty in a metre rule??
For a single value is it 1 mm or is it 1/2mm(half the smallest division) ? And what about measuring something like a length of a stick (we need to take 2 readings, and deduct them like 15-0=15), then is the uncertainty 1+1=2mm or is it .5+.5=1mm ?
Homework Statement
The exact question is in question one part ii of
http://www.xtremepapers.com/papers/CIE/Cambridge%20International%20A%20and%20AS%20Level/Mathematics%20(9709)/9709_s10_qp_11.pdf
Homework Equations
The Attempt at a Solution
For the first one I just pluged in a value for...
ANyone know how to draw a parallelogram/triangle to resolve force??
Homework Statement
http://www.xtremepapers.com/papers/CIE/Cambridge%20International%20A%20and%20AS%20Level/Physics%20(9702)/9702_s04_qp_2.pdf
question 1b
Homework Equations
The Attempt at a Solution
I drew...
Homework Statement
Hydrazine was used as a fuel for the Messerschmidt 163 rocket fighter in World War II and for the
American Gemini and Apollo spacecraft.
What is the enthalpy change of atomisation of 1 mol of gaseous hydrazine?
A 550 kJ
B 1720 kJ
C 1970 kJ
D 2554 kJ
Use of the...
Homework Statement
A garden fertiliser is said to have a phosphorus content of 30.0% ‘P
2
O5
soluble in water’.
What is the percentage by mass of phosphorus in the fertiliser?
A 6.55% B 13.1 % C 26.2% D 30.0%
Homework Equations
The Attempt at a...
Homework Statement
This question is pretty interesting, but a bit long, so bear with me
http://www.xtremepapers.com/CIE/International%20A%20And%20AS%20Level/9702%20-%20Physics/9702_w07_qp_2.pdf
question 5 part c
For (i) The width of each slit is increased but the separation remains...
I was attempting this question where I had to say which, out of graphite, diamond and sodium chloride represent a giant molecular structure? The answer is only the first two. Why is the latter excluded?
Homework Statement
Im having a bit trouble with diffraction gratings lately, with sums like this:
A parallel beam of light of wavelength 450 nm falls normally on a diffraction grating which has
300 lines /mm.
What is the total number of transmitted maxima?
A 7
B 8
C 14...
Homework Statement
A stone is dropped from the top of a tower of height 40 m. The stone falls from rest and air
resistance is negligible.
What time is taken for the stone to fall the last 10m to the ground?
A 0.38s B 1.4s C 2.5s D 2.9s
Homework Equations
The Attempt at a...
Homework Statement
http://www.xtremepapers.com/CIE/International%20A%20And%20AS%20Level/9702%20-%20Physics/9702_s07_qp_1.pdf
question 40
Homework Equations
The Attempt at a Solution
I got D, because the heaviest should have the lowest speed. But I am wrong. dnt know why
Homework Statement
http://www.xtremepapers.com/CIE/International%20A%20And%20AS%20Level/9702%20-%20Physics/9702_w10_qp_12.pdf
question 14
Homework Equations
mgh=gpE
fxd=workdone
The Attempt at a Solution
I HAVE NO IDEA WHY MY ANSWER IS WRONG!! AND THIS IS GETTING ME so...
Homework Statement
http://www.xtremepapers.com/CIE/International%20A%20And%20AS%20Level/9702%20-%20Physics/9702_s11_qp_13.pdf
question 12
Homework Equations
moments=Fd
The Attempt at a Solution
60X20=50d
d=24cm
The question is from http://www.xtremepapers.com/CIE/International%20A%20And%20AS%20Level/9709%20-%20Mathematics/9709_w10_qp_13.pdf
question no. 7 (i). I think it should be more than easy for a functions fanatic( or someone who does math regularly for that matter) to get the right answer, but...
I dont understand how to calculate percentage uncertainty!?
I know in chem we calculate uncertainties by smallest division/the reading X 100. But in physics i am clueless. For instance heres an example
The power loss P in a resistor is calculated using the formula P = V^2/R.
The uncertainty...
Homework Statement
http://www.xtremepapers.com/CIE/International%20A%20And%20AS%20Level/9709%20-%20Mathematics/9709_s05_qp_6.pdf
question no. 6 part ii (Safety regulations state that the pressures must be between 1.9 − b bars and 1.9 + b bars. It is
known that 80% of tyres are within...
combination problem: A football team consists of 3 players who play in a defence....
Homework Statement
http://www.xtremepapers.com/CIE/International%20A%20And%20AS%20Level/9709%20-%20Mathematics/9709_s05_qp_6.pdf
7 a ii (if exactly one forward player must be included, together with any...
Homework Statement
http://www.xtremepapers.com/CIE/International%20A%20And%20AS%20Level/9709%20-%20Mathematics/9709_w03_qp_6.pdf
question 6 b ii
Homework Equations
The Attempt at a Solution
The concept is bothering me. the answer is 5! × 3! × 4C1. Why is it a permutation problem? Plus...
I can;t decide between trying for neurology or neuroscientist. All though I think neuroscientist would be a more interesting job, I do not like maths or chemistry( I love Bio and Physics). Being a neurologist would not only be satisfying aswell, but it will also pay aLOT! But the time of MBBS...
I want to be a neurologist in India. However it is horribly difficult to analyse all the courses involved and degrees needed to practise, through the net. It is frankly because there is hardly anybody with the correct knowledge and those with the knowledge hardly reply. I just want a basic blue...
Concentrated sulphuric acid is added to separate solid samples of sodium chloride, sodium
bromide or sodium iodide.
With which sample(s) does sulphuric acid act as an oxidising agent?
A sodium chloride only
B sodium chloride and sodium bromide
C sodium bromide and sodium iodide
D...
Homework Statement
http://www.xtremepapers.com/CIE/International%20A%20And%20AS%20Level/9701%20-%20Chemistry/9701_s11_qp_12.pdf
question 10
Homework Equations
The Attempt at a Solution
The way I am doing it, is to get two equations in terms of x and y and then equate them. For the...
Homework Statement
http://www.xtremepapers.com/CIE/International%20A%20And%20AS%20Level/9702%20-%20Physics/9702_s02_qp_2.pdf
question no. 7b
Homework Equations
dsin∅=nλ
The Attempt at a Solution
I subtracted the two angles and got 26 degrees. So then I plugged...