Calculating Final Velocity of 4kg Block with T=35N

[jisun.hong]

Homework Statement

You have a 4kg block attached to a string with T=35N. If the block begins at 5m/s and is lowered 10m what is approxaimate final velocity of block?

So I got the question right:
Find Fnet and times it by 10m and set (Fnet)(10)= work = KE and find velocity from KE.

But my question is W= PE + KE so where is the PE?

Thanks for the help.

 

[rock.freak667]

Homework Statement

You have a 4kg block attached to a string with T=35N. If the block begins at 5m/s and is lowered 10m what is approxaimate final velocity of block?

So I got the question right:
Find Fnet and times it by 10m and set (Fnet)(10)= work = KE and find velocity from KE.

But my question is W= PE + KE so where is the PE?

Thanks for the help.

$$PE=mgh$$

h=10

 

[PhanthomJay]

Homework Statement

You have a 4kg block attached to a string with T=35N. If the block begins at 5m/s and is lowered 10m what is approxaimate final velocity of block?

So I got the question right:
Find Fnet and times it by 10m and set (Fnet)(10)= work = KE and find velocity from KE.

The net work done by all forces is the change in KE

But my question is W= PE + KE so where is the PE?

Thanks for the help.

The work done by non-conservarive forces is the change in (KE +PE). You should carefully note the differences between the 2 equations. The latter incorporates the work done by gravity or other conservative forces in the PE term.