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## Want to learn fast? Be SMART!

In this busy world everyone wants to save time. Being students, learning is our primary job. To save time, we need to learn faster. But how?

The first step is to have a SMART goal!

S – Specific

M – Measurable

A –  Achievable

R – realistic

T – Time Bound

Having a Specific Measurable Achievable Realistic and Time Bound – SMART goal will increase your efficiency to grasp ideas faster.

While all of you may be having a long term goal, usually what you want to become after studies, you should have a short term goal, an objecting for every sitting of your studies too.

Have a Time Table – be specific what to study and when.

In the time slot for each, decide what and how much to study before you start. Know the outcome expected of you as a result of reading the portion. If it is not mentioned already, it is better to have a look at the questions based on the portion at hand before you actually read the topic.

Learn to read fast. Don’t go word by word while you read. Try to grasp a group of words at a go concentrating on the idea contained. Concentrate fully keeping in mind the objectives/ the questions you read based on the portion.

Do not reread or skip back until you have completed

Practice this daily and try to improve your reading and comprehension skills. This will certainly help you to score more as well as to live well in times to come.

## How to determine the diameter of a rod using thread an meter scale?

You are given a sufficiently long piece of thread, a meter stick and a thin round shape iron rod. Explain how would you measure the diameter of iron rod by using given thread and meter stick.

Wind the thread over the rod  closely a number of times say 20 and mark the end point. Now unwind it and measure the length of the thread used to wind over the rod.

This length = n x 2πr, where n is the no. of windings and r is the radius of the rod.

Therefore, the diameter of the rod = 2r = The length of wire used for ‘n’ windings /nπ

## The Physics of Breaking Stuff – The Physics of Martial Arts

How is Physics applied in Breaking things in Karate Demonstrations?

The following video explains it well. If you have further doubts, please post them as comments to this post.

## How wheel + Tyre diameter affects a vehicle’s speed

I have been told a larger wheel/tyre decrease acceleration because its harder to turn the wheel making the car rev slower.

But the same person tells me it will increase the top speed.

My question is if the car has a max rev of 8000rpm but only reaches 7000rpm in its highest gear would a smaller wheel/tyre not make it easier for the car to rev higher thus possible increasing the top speed by using a smaller wheel?

As wheel radius increases, its top speed increases for a given RPM since for a given RPM the speed of the vehicle is directly proportional to its radius.
The distance traveled in one rotation = 2 π R
But now, there is another effect also here. As the radius of tyre increases, its moment of inertia increases and it would be harder for the engine to rotate it. So, the engine will not be able to turn it with the same ease as before, but however, there will be an increase in top speed other conditions remaining the same.
Refer to http://wahiduddin.net/calc/calc_speed_rpm.htm for a calculation of top speed vs tyre radius

## DECREASING PRESSURE BY INCREASING AREA

The pressure exerted by a given force can be decreased by increasing the area of contact.

# P=F/A

The equation shows that pressure is inversely proportional to area.

## FOUNDATION OF BUILDINGS

The foundation off building is made more broader than the rest of the building so that the pressure exerted by the weight on earth can be decreased.

## SHOULDER STRAPS OF SCHOOL BAGS

The shoulder straps of school bags are made wider and soft so that the pressure exerted by the heavy bags on shoulders can be reduced. You can feel the paining pressure if you try to replace the broad strap with a narrow one.

FEET OF ELEPHANT AND CAMEL

## MILITARY TANK

The Military tanks have a broad chain so that the pressure exerted by the heavy vehicle on ground is a minimum and it can travel even through marshy places

• Heavy Vehicles have more tyres
• When vehicles get struck in marshy places, wooden planks are used for the vehicle to come up.

## 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 much essential to prepare well in advance.

Know the fundamentals

Knowing the fundamentals is the first step. Learn your daily lessons well. In learning Physics, “Questioning Every Answer is more important than Answering Every Question”

Whenever you learn a new concept, try to get all the doubts clarified. Ask doubts and questions to your teachers. (If they don’t answer you satisfactorily, post them at www.askphysics.com )

Observe your surrounding and try finding examples on what you have learnt. The syllabus and books give you a framework on what to study; but don’t just limit your studies on books and syllabus. Search related information from real life and other sources of reference.

RECOMMENDED BOOKS FOR IIT JEE PREPARATION

The very first book you cannot avoid is the NCERT TEXT BOOK for class XI and XII

These books are designed after thorough research and the exercises are carefully added. Be sure to solve all the exercises including the Additional Exercises

Here are some of the Books you can refer for practicing for IIT JEE

1. Concepts of Physics (by H C Verma)
2. Fundamentals of Physics (by Resnick, Hallidey)
3. University Physics (Zemansky)
4. Problems in Physics (IE Irodov)

By the by, having too much books will be a hindrance. It is better to start with the NCERT books and after mastering all the exercises take up Resnick Hallidey and after clarifying the concepts take up Problems from H C Verma’s concepts of Physics and then go on to IRODOV if time allows.

Wish you all the best.

## Solving problems from kinematics and friction

I just want to know how to easily solve problems related to kinematics and friction. I don’t know why i always face problem in these two topics a lot……
THANK U

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