# Search results

1. ### Rotation in space.

We have a rod and keep floating in ISS. If we tap giving force at one end, will it, 1. Rotate about an axis or 2. Has translational and rotational motion. If it rotates, where is the axis? I have interest in yoyo motion too. From YouTube, they spin them while holding. Can we rotate yoyo from...
2. ### Transit of Venus

A transit of Venus across the Sun takes place when thplanet"etVenus passes directly between the Sun and a superior planet, becoming visible against (and hence obscuring a small portion of) the solar disk. During a transit, Venus can be seen from Earth as a small black disk moving across the face...
3. ### Electric Field Intensity. Finite sheet of charge.

problem statement, all variables and given/known data A finite sheet of charge, of density ρ=2x(x2+y2+4)^3/2, lies in the z=0 plane for 0≤x≤2m and 0≤y≤2m.Determine E at (0,0,2)m Ans:(18x10^9)(-16/3ax-4ay+8az) Homework Equations E=kQ/R2 The Attempt at a Solution dE=ρdA / R^2 aR...
4. ### Electric Field Vector

Homework Statement From attachment R=-xaa-yay+3az Homework Equations The Attempt at a Solution I see 4 different values, one for each quadrant. 1st.quadrant R=+xaa-yay+3az 2nd. quadrant R=-xaa+yay+3az 3rd. R=-xaa+yay+3az 4th R=-xaa-yay+3az Where did I go wrong in determine value of R?
5. ### Electric Field Intensity

Homework Statement Show that the electric field E outside a spherical shell of uniform charge density ρs is the same as due to the total charge on the shell located at the centre. Homework Equations Using only Coulomb's Law E=Q/4πε0 ar The Attempt at a Solution If i assumed it as circular...
6. ### Coulomb Forces

Homework Statement Find the force on a point of charge of 30μC at (0,0,5)m due to a 4m square int he z=0 plane between x=±2m and y=±2m with a total of 500μC, distributed uniformly. Homework Equations The Attempt at a Solution R=-x,-y,+5z dQ=ρdydx=500/4 dydx dE=dQ(5az) / (4πε0((x2+y2+25)3/2...
7. ### Spherical coordinates vector

Homework Statement Find the vector directed from (10,3π/4,π/6) to (5, π/4,π), where the endpoints are given in spherical coordinates. Ans -9.660ax, - 3ay. + 10.61az Homework Equations az=rCosΦ The Attempt at a Solution az=10Cos(π/6) +5Cos(π) =13.6 My answer differs. Where did i go wrong?
8. ### Probability of placing marbles in a compartment

Homework Statement 1. (a) A shelf contains 6 separate compartments. In how many ways can 4 distinguishable marbles be placed in the compartments?(b) Work the problem if there are n compartments and r marbles. This type of problem arises in physics in connection with Bose-Einstein statistics...
9. ### Rotational Inertias.

How to derive the Rotational Inertia for a flat plate. I do not see any symmetry about the axis of rotation as in a thin rod. http://imageshack.us/a/img845/1134/53433231.jpg [Broken]
10. ### There is a kingdom where if a person drinks poison he will die. The

There is a kingdom where if a person drinks poison he will die. The only way to counteract the poison is to drink a stronger one. Then the reaction stops. The king decides that he must have the strongest poison available in his possession. So, he sets up a contest between his court adviser and...
11. ### For each real number x, let f(x) be the minimum of the numbers 4x+1,

For each real number x, let f(x) be the minimum of the numbers 4x+1, x+2, and -2x+4. What is the maximum value of f(x)?
12. ### Torque and momentum.

Sorry the title should be : Impulse and Momentum 3000Solved Problems in Physics-Shaum's 9.6: A camper lets fall a heavy mallet of mass M from the height y upon the top of a tent stake of mass m and drives it into the ground a distance d. Find the resistance of the ground, assuming it to...
13. ### Unit of Torque

Why unit of torque is not m.N 1.Torque=rFSinθ =>m.N 2. 1 N.m = 1 Joule but 1 N.m in torque ≠ 1 Joule For the above 2 reasons i reckon it should have unit of m.N.

If we are to answer multiply questions on a single topic, do the step is vital. For example question#5, do we have to get answer for question 5(a) before we are able to do question b(b). Does it mean the first one is the easiest? Thank you.
15. ### Maybe triangle inequalities theorem

Homework Statement Prove: If a2+b2=1, and c2+d2=1, then ac+bd ≤1 Homework Equations Maybe triangle inequalities theorem. The Attempt at a Solution
16. ### Newton's Laws of Motion

At the instant that one-fourth of block 1 remains on block 2, x2+l=x1+(l/16). For days trying to figure out how this equation derived from. Thank You. http://img15.imageshack.us/img15/3926/kotak.jpg [Broken]
17. ### Limit homework issue

Homework Statement If f(x)=x2 prove that \lim_{x \to 2} f(x)= 4 Solution given: We must show that given any ε >0, find δ >0 such that |x2-4|<ε when 0<|x-2|<δ Choose δ≤1 so that <|x-2|<1 ----------------------------------------------- Confuse between the word 'find' and 'choose'.
18. ### Work and Energy

A vertical spring with constant 200N/m has a light platform on its top. When a 500-g mass is set on the platform, the spring compresses 0.0245m. The mass is now pushed down 0.0755m farther and released. How far above this latter position will the mass fly? The answer from the book. If it does...
19. ### Quantum World

I watch a series on quantum world. The host said particles can pass through each others. And then he pushed a wall and said if he keep on pushing for billion of years, there will be possibilities he will pass through the wall. We have more than 7 billions people in this world. I never heard...
20. ### The WMAP objective is to measure the temperature differences in the

The WMAP objective is to measure the temperature differences in the Cosmic Microwave Background (CMB) radiation. My question are, 1.How to distinguish all the radiations of 13 billion years ago from others of the latter ones. 2.How the distance of radiation source is measured. Thanks.
21. ### Amgular impulse

How far above its center should a billiard ball be struck in order it roll without any initial slippage? Denote the ball's radius by R, and assume that the impluse delivered byt the cue is purely horizontal Book Solution: Since any static frictional forced supplied by the table is limited...
22. ### Really couldn't catch the concept on epsilon and delta in limits

Really couldn't catch the concept on epsilon and delta in limits. Let ∂x=x2 - x1 In finding a gradient the value ∂y is taken at certain value. But in finding area using integral, the ∂y is seen to taken as zero. F(x2)=F(x1) Maybe one multiplication and the other is division.
23. ### Depletion region- diode

At depletion layer of p region, there more negative ions thus negatively charged region. Likewise at n region, it is positively charged. Then why in equivalent forward bias the diode behave as a battery of .7v with positive at depletion region of the p region where it is negatively charged?
24. ### Probability- My poor English

Find the probability of scoring a total of 7 points (a) once, (b) at least once, (c) twice, in 2 tosses of a pair of dice. My question. 1. What does scoring a total of 7 points mean? Is it 1+6 or 2+5 or 3+4 or 4+3 or 5+2 or 6+1 2. Is in 2 tosses of a pair of dice means that throwing 2...
25. ### Rotational motion, frictionless.

http://img444.imageshack.us/img444/8148/rollwx.jpg [Broken] A rope is wound around a cylinder of mass 4kg, and I=0.02kg.m2 about the cylinder axis. The frictional force between table and cylinder is negligible. Solution: a=20/4=5.0m/s2 α=ar is not applicable when slippage occurs...
26. ### Dynamic of Ratational Motion

If the ball were rolling uphill, the force of friction would still be directed uphill as in FJg. 1O.19b. Can you see why'? http://img252.imageshack.us/img252/4516/rollingm.jpg [Broken] I always assume the friction is always in opposite direction of the motion.
27. ### Deep freeze

Today i watched Discovery about the fate of the universe. One of the presenters said that finally all the energies used up and the universe will be in deep freeze. My question is where all the energies go? What about conservation of energies? Thank you.
28. ### Inequalities #2

Homework Statement a. Prove: If a≠b≠c are real numbers, then a2+b2+c2>ab+bc+ca b. Prove: If a>0, b>0and a≠b, then a/b+b/a>2 Homework Equations (real numbers)2>0 The Attempt at a Solution a. (a+b+c)2>0 a2+b2+c2>-2(ab+bc+ca) Try to prove -2(ab+bc+ca) > ab+bc+ca but not true, -2.4...
29. ### Centrifugal force

"Centrifugal force" Homework Statement A smooth horizontal tube of length l rotates about a vertical axis. A particle placed at the extreme end of the tube is projected towards O(axis) with a velocity lω while at the same time the tube rotates about the axis with constant angular speed ω...
30. ### Prove the inequality?

Homework Statement Prove: If a>b and c>d, then a+c>b+d Hint: (a-b)+(c-d)=(a+c)-(b+d)>0 Homework Equations The Attempt at a Solution How to use the hint to prove the inequality? My method, not sure it's right. Given c>d, c-d>0 Given a>b => a+(c-d)>b Thus a+c>b+d