IIT JEE , AIEEE Forum - Physics , Mechanics

nrki99

chapter-8 work, power and energy ques-48 h.c.verma

vasanth

can u plzzz post the question

vish0001

work done by all forces = net change in kinetic energy !

nrki99

hey vish, please tell whole soln.

vish0001

ok, just a moment, i am typing !!

vish0001

see, the compression in the spring is given as 5.0 cm. this means u can find out the work done by the spring, now, simply apply energy conservation ::

work done by all forces in the x- direction = net change in kinetic energy in the x- direction.

-1/2 k x² = 1/2 m (v₂ ²- v₁²)

(we have not considered the work due to mg as mg is bringing kinetic energy in the y direction whereas at this moment, we require the velocity in the x direction)

now, find the value of v_2.now, horizontal distance covered = v₂* t (let 't' be the period of travelsion).------------------------------------------ (1)

now, the object travels the vertical distance also in the same time ! so,

now : work done by all forces in the y direction = net change in kinetic energy in the y direction !

=> 1/2 m (v_2^'² - v_1''²) = mg(h2 - h1 ) (v1'' = 0 )

now, find v₂ ' and then find out time through the laws of motion equation and find the distance by substituting it in the equation (1)

vish0001

hope i am clear !

nrki99

i think u have a hard work here so i am giving u 2 salutes.please help me in physics in other topics as well.sorry vasanth , i did't write question

vish0001

no probs man !! always there to help u !!

vish0001

any other doubt ?

nrki99

thanks for ur support.presently i have no problem.i ask the prob. from u

tommorow. is it ok.....

nitinpaliwal

1/2kx.x=1/2mv.v
1/2.100.5/100.5/100=1/2.100/1000.v.v
v =

5/2

h=2 vertical
1/2g.t.t=2

t=

2/5

horizontal dis=v.t=1 ans

arnold

hey nitin how u have taken initial velocity equal to zero please explain

nitinpaliwal

initial velocity along vertical direction is 0
but along horizontal direction is v

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