Physics : Tips & Tricks

**How to Solve any Physics Problem :**

1. Draw a Rough Diagram
2. List down the knowns and unknowns
3. Use the best Equation
4. Solve it Symbolically
5. Arrive on an Answer

**Additional Critical Tips :**

1. For Graphs , use only formulae . Substitute different values to obtain the graph .
2. In case of questions on force or components ; look for al the important forces/components .
3. If all particles of a body are contributing to a quantity , e.g. Moment of Inertia , Gravitational Field , Electric Field , Magnetic Field ; then find the quantity for a small elemental area and then integrate it between appropriate limits .

## Measurements

1. Use dimensional analysis to eliminate options . Try to match dimensions .

## Scalars and Vectors

1) If in any question , based on any chapter , direction is being asked , then always work with vectors (xi + yj + zk)

## Kinematics

1. Preferably make use of Kinematical Equations only .
2. For 2 dimensiional and three dimensiona motion , break down the motion into 2/3 components and apply kinematic equations to ach independently . (e.g. Projectile Motion )

## Force

1) **Working with Newton's Laws of Motion**

i. Select the system

ii. Identify the forces

iii. Make a free body diagram

iv. Choose and write Equations

**2) Working with Tension in String :**

## Work, Energy and Power

The concepts of Work and Energy can be applied to all MCQs , dealing with momentum , force , velocity , acceleration and height .

## Friction in Solids and Fluids

1. For friction , draw the free body diagram and resolve the vectors . Mostly , the free body diagram is standard , so you can learn the resolved forces beforehand .

## Rotational Motion

1. For a system of bodies , add up their individual moments of inertia .

## Electrostatics

1) For repulsive force between two like charges , the closest distance of approach is when Kinetic Energy is equal to Potential Energy .

2) For questions related to Flux and Electric Field Intensity , consider **Gauss Theorem** .

3) The formulae for E , at diffrent distances from a conductor , circular conductor and at centre of circular conductor is the same as B .

## Current Electricity

1. For solving resistances in series and parallel , draw a simpler equivalent diagram of circuit .
2. When n resistors of Resistance R are connected in series , the total resistance is nR .
3. When n series of Resistance R are connected in parallel , the total resistance is R/n .
4. If a wire of resistance R is stretched n (l2/l1) times , The new resistance is n2R
5. When a complicated symmetric circuit is given for finding resistance , it can be divided into halves to simplify the circuit .
6. When simplifying a circuit , plot points on the circuit to guide you .
7. In Wheatstone's network , if the network is balanced , the middle resistance is ignored because no current flows through it .
8. Whenever , a part of circuit confuses you , remove it and see it's role in the circuit .
9. The effective resistance for a balanced Wheatstone's Network is R
10. For equivalent resistances , consider current through each branch .
11. Use Kirchoff's laws for complicated circuits .