Question

the P.E of body at height of 3m from the ground is 30J.its K.E AT HEIGHT OF 1m will be (g=9.8m/s^2)

Answer 1

Is this a question?

Answer 2

yes :)

Answer 3

Hmmm

Answer 4

*puts on thinking cap*

Answer 5

ok :)

Answer 6

\[E_i = E_f\]
\[PE_I + KE_i = PE_f + KE_f\]
\[PE_I +\cancel{ KE_i} = PE_f + KE_f\]
\[PE = mgh\]
\[ PE_{3m} = mg(3m)\]
\[PE_{3m}=PE_{1m}+KE_{1m}\]
\[KE_{1m} = PE_{3m}-PE_{1m} \]

Answer 7

30 - 10 = 20 J .am i right @AllTehMaffs

Answer 8

and y we cancelled initial K.E ?

Answer 9

Kinetic energy only applies if the object is moving; the problem doesn't say that is is, so I think we can assume that it starts at rest. And you're right :) How did you get that answer though?

Answer 10

P.E = mgh