28 - Work, Energy and Power Questions Answers
A bomb of mass M @ rest explodes into 2 fragments of masses m1 &m2 . The total energy released in the explosn is E if E1 &E2 represent the energies carried by m1 &m2. then which of the followg is correct
a) E1=(m2/M)E
B) E1= m1/m2 E
C) E1= m1/M E
D) E1= m2/m1 E
(1) is correct
the ratio of energy will be E1/E2 = m2/m1
a small body starts sliding from a height h down an inclined groove passing into a half circle of radius h/2. find the speed of the bodywhen it reaches the highest point of its trajectory
since body starts from height h at rest and ends in the same height so it will again be in rest
A smooth sphere of radius R is made to translate in a straight line with constnt acceralation a . A particle kept on the top of the sphere is released from there at zero velocity with respect to the sphere. find the speed of the particle with respect to the sphere as a function of the angle θ it slide
use energy conservation to solve it
if not possible then send a reply we will give you complete answer.
How fast a car can pull 100kg Iron? the energy of car is 10hp
E= ∫Fds
= ∫ma ds
= ∫m( dv / dt) ds
= ∫m dv (ds/dt)= ∫mvdv
= 1/2 mv2
so v =(2E/m) 1/2 now use mass 100kg & given energy after converting in SI units
This answer is given by SARIKA SHARMA and is correct, we made some modifications only
consider a small segment of chain at angle β from top, its length = Rdβ and mass = mRdβ/L
its potential energy = [mRdβ/L]gRcosβ now integrate it within the limits 0 to L/R
for getting the answer of the second part calculate potential energy twice once between the limits 0 to L/R and then between the limits θ to θ+(L/R)
then difference of potential energy = KE of the chain. solve it ?
for getting third part differentiate v obtained in the second part with respect to t, dθ/dt will be ω and it will be v/R
finally put θ and t = 0 for getting the answer.
IN THE PREVIOUS QUESn THAT WAS BALL IS DROPPED FROM HEIGHT 5M ACC. DUE TO GRAVITY IS NOT KNOWN & WE HAVE TO FIND = IT LOSES ITS VEL. BY WHICH FACTOR WHEN IT RISES TO 1.8M
IN THE SOLn SUBMITTED BY SOMEONE HE HAS TAKEN ACC. WHILE FINDING VEL EQN= =V2-U2=2AS AS CONST. SO I WANT TO KNOW WHY IN THIS QUES ACC. IS TAKEN CONST. WHILE THERE IS NO MENTn IN QUES
answer by Nikhil is correct
consider once agian
a small block of mass m is kept on a rough inclined surface of inclination o * fixed in an elevator the elevator goes up with a uniform velocity v &block doesn't slide on the wedge the w.d by the force of fricition on block in t time is?
ANS) mgtsin2o*
work done by the force of fricition on block in t time = fvtcos(90-θ) = mgsinθvtsinθ 
TWO EQUAL MASSES ARE ATTACHED TO TWO ENDS OF A SPRING CONST. k THE MASSES ARE PULLED OUT SYMMETRICALLY TO STRECH SPRING BY A LENTH x OVER ITS NATURAL LENTH. WORK DONE BY THE SPRING ON EACH MASS IS -1/4kx2. HOW
total work done on the spring = 1/2kx2
so work done by the spring = -1/2kx2
this work is done on 2 masses so work done by the spring on 1 mass = -1/4kx2