Interesting Questions

Mirror Mirror Relativity

Can you see your image when you are travelling at the speed of light?

Visitors and students are requested to respond and answer via comments.

Einstein’s Theory of relativity says:”The Laws of Physics are the same in any Inertial Frame of Reference.”

Be the first to comment - What do you think? Posted by admin - November 17, 2011 at 8:34 am

Categories: Interdisciplinary physics, Interesting Questions, mirror mirror, Relativity, Research Tags: image, image formation, mirror, mirror mirror, relativity

Motion in a vertical circle and conservation of energy

A stone tied to a string of length l is whirled around a vertical circle with the other end of the string at the centre. At a certain instant of time the stone is at the lowest position and has a speed u. What is the magnitude of change in its velocity as it reaches a position where the string is horizontal?

Answer:

Let’s assume that the potential energy at the lowest position be zero. So, when the string is horizontal, the stone has risen by a vertical height l, the length of the string which is also the radius of the vertical circle.

If v is the magnitude of velocity at the horizontal position, then according to the law of conservation of energy,

KE+PE at the lowest position = KE+PE at the horizontal position

$\frac{1}{2}mu^{2}=\frac{1}{2}mv^{2}+mgl$

From the equation above, v-u can be calculated.

$v=\sqrt{u^{2}-2gl}$

The following links will help you for deeper understanding and you can browse through some solved problems from the topic too.

Be the first to comment - What do you think? Posted by admin - October 10, 2011 at 7:55 am

Categories: Answers, ANSWERS TO QUESTIONS FROM VISITORS, CLASS XI, energy loss, energy motion, Exam Help, General Physics, IIT JEE, Interesting Questions, motion work, Physics Homework, Plus Two Physics, power and energy, Problem Solving, Problems, Soved Numerical Problems Tags: Auto, centre, conservation of energy, law of conservation, law of conservation of energy, magnitude, motion, motion laws, position, stone, vertical circle, vertical height

Collection of Problems received from Class 12 Physics

These problems were posted by Geena. Hope that we will be able to post the answers to these questions soon; each in a separate post. By the time visitors can attempt to post their answers as comments to this post. (Only selected posts will be published) Please note that the answers are not published until the [...]

Which books should be referred for IIT JEE ?

We have received hundreds of questions on the above subject. As the questions continue to pour in, we found it necessary to create a post on it. IIT JEE is an entrance exam of international repute and IITs are considered at par with MIT by many. So, if you are an IIT aspirant, it is very [...]

Why protons attract inside a nucleus?

What is the reason for proton- proton attraction inside the nucleus according to nuclear physics? (Sanjeev Asked)

Answer: Inside the nucleus where the nucleons are very close to each other, the force which holds them together is the nuclear force, which is the strongest force in nature. The electrostatic force between protons is negligibly small compared to the nuclear force. But the nuclear force is of a very short range, 10^-15 m.

The nuclear force is charge independent, i.e; the nuclear force between proton and proton, proton and neutron as well as neutron and neutron are almost the same.

Yukawa’s meson theory suggest that the nuclear force is an exchange force. The nucleons are bound because of constant exchange of the mesons.

The nuclear force is only felt among hadrons. At small separations between nucleons (less than ~ 0.7 fm between their centers) the force becomes repulsive, which keeps the nucleons at a certain average separation, even if they are of different types. At distances larger than 0.7 femtometer (fm) the force becomes attractive between spin-aligned nucleons, becoming maximal at a center-center distance of about 0.9 fm. Beyond this distance the force drops essentially exponentially, until beyond about 2.0 fm separation, the force drops to negligibly small values.

At short distances (less than 1.7 fm or so), the nuclear force is stronger than the Coulomb force between protons; it thus overcomes the repulsion of protons inside the nucleus.

However, the Coulomb force between protons has a much larger range due to its decay as the inverse square of charge separation, and Coulomb repulsion thus becomes the only significant force between protons when their separation exceeds about 2 to 2.5 fm.

(There are many terms introduced in the explanation. You can discuss them as comments for obtaining further details, if required)

Reference:

Be the first to comment - What do you think? Posted by admin - at 7:32 am

Categories: +2 Physics, Answers, ANSWERS TO QUESTIONS FROM VISITORS, Chemistry, interesting question, Interesting Questions, Nuclear Physics Tags: answer, attraction, coulomb, coulomb force, coulomb repulsion, femtometer, Force, meson, meson theory, nuclear force, nucleus, Physics, proton, range, reason

Is the acceleration due to gravity different in south pole and north pole

Mohak Tandon Asks – “ “Is the acceleration due to gravity different in south pole and north pole?” Answer: As per theory, acceleration due to gravity changes with altitude, depth and latitude. If we consider that the variation of g with latitude is caused by rotation of earth only, then the value of g will be same for both [...]