# Why is tension added with mg?

#### abhistud

Why is my teacher saying that T = mg + ma = 24 N?

Shouldn't it simply be 4 N?

https://ibb.co/dHiDkk

#### skeeter

because ...

$F_{net} = ma$

Tension is directed upward, force of gravity is directed downward ...

$T - mg = ma$

$T = mg + ma \implies T = m(g+a)$

#### AKM17

because ...

$F_{net} = ma$

Tension is directed upward, force of gravity is directed downward ...

$T - mg = ma$

$T = mg + ma \implies T = m(g+a)$
Yes you are right!
What I like about these tasks, the fact that they can be solved with the help of the system of equations and the transfer of terms.

Last edited by a moderator:

#### THERMO Spoken Here

Hi AKM17

Yes, the math works. Set it up and use its operations. (Note: "Net" is not a math operation.
A net is for catching butterflies).

Don't know your level but here is more reading (of possible interest).