Solving the Tension in a String Attached to a 10 kg Block

[JohnD623]

Homework Statement

A string is attached to a 10 kg block that lies on a horizontal surface. If the string is pulled horizontally with a force of 50 N, friction acting against it is 30 N. What is the tension in the string?

Homework Equations

F = ma

The Attempt at a Solution

Would it be 50 N? Friction wouldn't matter. Or does it matter? The answer is 80 N?

 

[NascentOxygen]

Hi JohnD623! http://img96.imageshack.us/img96/5725/red5e5etimes5e5e45e5e25.gif

the string is pulled horizontally with a force of 50 N,

End of story!

The tension in the string is the force it carries, 50N.

To take this question further ...
30N overcomes friction, so how to account for the other 20N?