Water drops from the roof of a building 10 m high. The drops fall at regular intervals of time, the first drop striking the floor at the instant the 4th drop begins to fall. Find positions of individual drops,when a drop strikes the floor?
Let t is the time interval between A,B,C and D positions That means, 3t second taken to travel from A to D. That is, 10 m traveled in 3t seconds.
The earth has on electric charge that causes an electric field near its surface of the order of 100 vm-1.What is the surface density of charge on earth of earth is a conducting sphere? pls help me 2 solve it
Anish V Rajan said...
Take earth as a conducting sphere of surface charge density (sigma)
Assume total charge that is spread on the surface is Now concentrated on the center. Find Electric field at the surface by usual equation
Q1 Certain physical quantities are listed below. Select any three pairs of physical quantity with same dimension. (1) Stress (2) Energy (3) Displacement (4) Force (5) Work (6) Pressure (7) Torque (8) Weight (9) Velocity
A1.Stress & Force, Energy & Work, Force & Weight
Q2 In the above question, Select the odd one ? Write the uses of dimensional analysis ?
A2.odd one is Torque because it is related to circular motion.
Uses of dimensional analysis are I. Check the correctness of an equation II. Derive an equation relating to two or three physical quantities III. Find dimension of constants in an equation IV. Convert unit from one system to another.
Q1.A balloon raises with constant velocity 10 m/s. A load tied by a rope to the balloon is cut when it is at a height of 500 m. (a)How long will it take to reach the ground ?
A1.
Here Initial velocity u = 10 m/s ( Positive , since direction of initial motion is positive)
Displacement , S = - 500 m (towards downward - against initial motion direction)
Acceleration (due to gravity) , a = - 9.8 m/s2 (also downwards - against initial motion direction)
When two or more waves travel in a medium, along a straight line, simultaneously, then net displacement of any particle is the algebraic sum of displacement produced by the individual waves separately.
This principle work good for mechanical waves and electromagnetic waves, provided their amplitude is not very large.
Bounded Medium:
A medium bounded by definite boundaries. Boundary can be of two types
[1] Free boundary
[2] [2] Rigid or Fixed boundary
Let both end of a string be Free. Transverse wave / pulse propagates along the string is get disappear while reaching at the other end. Mean time, another pulse appear to come back from the free end. Here there is no change in phase ( π = 0) of the reflected pulse.
If equation for incident wave
y = A sin (wt - kx)
Then the equation of wave reflected from the free ind will be
y = A' sin (wt + kx)
Wave / pulse reflected from Free boundary.
If the displacement of particles in incident pulse is upward, then the displacement of particles in reflected pulse is downward and vice versa. This mean wave or pulse reflected from a rigid boundary , it undergos a phase change of 180 degree.
If the equation for incident wave, propagated along +ve X axis :
y = A sin (wt - kx)
Then the equation for wave reflected from rigid end will be
y = A' sin (wt + kx + π )
Here A' is the amplitude of the reflected wave
(x) is replaced by (-x) because reflected wave travel in opposite direction
( π ) is the phase difference between incident and reflected wave.
Production of Stationary wave
When two waves of same frequency and Amplitude travel in opposite direction in a straight line, at the same speed, they superimpose each other and a new wave is formed. It is called Stationary wave.
