Question

My math is wrong on this problem but why?

Answer 1

Part A:
\(PE=KE=mgh=\frac{1}{2}mv^2=gh=\frac{1}{2}v^2\)
\(=9.8m/s^2(10-30)m=\frac{1}{2}(v^2_f-10^2m^2/s^2)\)
Is 10m the final height ??? That gave me a -20 and it made the final velocity \(v^2f=-292 m/s\) which is wrong because i can't take a square root of a negative number...

Answer 2

isnt PE+KE=constant
thus
PE1+KE1=PE2+KE2
PE1-PE2=KE2-KE1

Answer 3

That's right
PE1+KE1=0
SO PE1=-KE1 that's probably the error i have in this question

Answer 4

no no, its not equal to zero
you have 2 states

Answer 5

assuming that the total energy of state 1 is equal to total energy of state 2, then the difference would be zero
but its best to assume the total energy of any given state is a constant, not zero

Answer 6

Here's what i am thinking