A body of mass 2 kg is thrown vertically upwards with an initial velocity of 20m/s. What will be its potential energy at the end of 2s ? ( Assume g = 10 m/s^2).
NOTE ANSWER IS NOT 400 IN MY BOOK IT IS WRITTEN 300
devankoberoi2003:
PLEASE TELL. I HAVE A PHYSICS EXAM.
I HAVE CALCULATED AND ANSWER IS COMING 400. BUT BOOK SAYS IT IS 300
BOOK SAYS THAT MAXIMUM KINETIC ENERGY IS 400 JOULES. BUT KINETIC ENERGY AT THE ENERGY AT END TO 2 SECONDS IS 300
I have calculated the maximum kinetic energy by formula 1/2 Mmv*v but i am not able to find kinetic energy at end to 2 seconds
according to me they both must be same, but book has 300 and other 400
PLEASE HELP NOW.
No, u r not wrong my friend
seems like book has got a printing mistake
Answers
Answered by
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Hey !!
Calculate height reached in 2s, using the kinematic equation,
that is, s = ut+1/2at^2
u =20m/s, a=-10m/s ,t=2 and s=h1
So,
h1=20*2-1/2*10*2^2
=20mtrs
hence Potential energy after 2s ,P.E.1 =(2kg)(10m/s^2)(20m)
= 400J
hope i helped u plz mrk it
Calculate height reached in 2s, using the kinematic equation,
that is, s = ut+1/2at^2
u =20m/s, a=-10m/s ,t=2 and s=h1
So,
h1=20*2-1/2*10*2^2
=20mtrs
hence Potential energy after 2s ,P.E.1 =(2kg)(10m/s^2)(20m)
= 400J
hope i helped u plz mrk it
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