Messages posted by Juhi Sharma

q=It

=7.5*45

=337.5C

I=0.7A

dividing by e the magnitude of charge on single electron we get

the number of electrons per second

=.7/(1.6*10^-19)

=4.4*10^18

the rate of flow of electric charge across a given area is called current

I=dq/dt

the current density is the quantity whose direction is the same as current but magnitude is current per unit area.

J=I/A

I=integration of J.ds

let resistance of wire at temperature T0=R0

resistance of the wire at temperature T

=R

=R0+aR0(T-T0)

where a is temperature coffitient of the resistance of the material of the wire

R=roh(l/A)

where roh is a constant called resistivity

it depends in the material of the conductor

units=

R=ohm

roh=ohm.m

the potential difference across a battery with a negligible internal resistance is equal in magnitude to the emf

as a charge passes from the baterry the non electric forces do work qE on it .

if q is +ve the +ve work

the electric forces on the other hand do an equal amount of negative work and the electrostatic system gains electric potential energy.

the term internal resistance refers to the resistance within an emf source

a galvanometer is an instrument for masuring very small electric currents;

it underlies both voltmeters and ammeters.

the electromotive force (emf) of a source is the energy per unit charge converted from chemical or some other form of energy to electrical energy

the emf is one volt when each coulomb of charge recieves one joule of energy.

by archimidies principle

roh1Vg=roh2(3V/4)g

this gives

roh2=4/3roh1

F1/A1=F2/A2

F1=200/5*250

=10kN

delta P=F/A

=5000/pi*r^2

=63700lb/ft^2

=44.2lb/in^2

before collison

L0=Rmv

after collision

Lf=(mR^2+I)w

L=Lf

w=mvr/(mR^2+I)

I0w0=Iw

I0=2Mr^2/5

I=2Mr1^2/5

w=(r/r1)^2w0

I1w1=I2w2

1.33*1.9=0.48w2

w2=5.26

power= tou*w

=.8{[1400(2*pi)]/60}

=117.3W

using 746W=1hp

P=0.157hp

the power delivered by the moter is touw

therefore tou=.2/1400

=149/147

1.02Nm

net torque =(1600-500)*.4m

=440

w=10pirad/s

net power delivered=tou * w

=440*10*pi=4400pi

net power generated=.9*4400w

=12.4kW

power=P=tou*w

P=2hp

=1492W

w=30pi rad/s

tou=1492/30*pi

1508Nm

the work done by a xonstant torque in turning through an angle theta is tou*theta

then K of the wheel = work by stopping torque

so 1/2Iw^2=tou*theta

tou=.5*20*(6pi)^2/40*02*pi

=1401Nm

KE=1/2Iw^2

I=Mk^2

=25*.22^2

1.21

KE=1/2*1.21*(12pi)^2

=860J

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