Physics; two forces on an object

[triplel777]

Homework Statement

Two forces FA and FB are applied to an object whose mass is 16.0 kg. The larger force is FA. When both forces point due east, the object's acceleration has a magnitude of 0.900 m/s2. However, when FA points due east and FB points due west, the acceleration is 0.400 m/s2, due east. Find the magnitude of FA and the magnitude of FB.

Homework Equations

The Attempt at a Solution

well Fnet= Fa+Fb= ma
so Fnet = 16*0.9
Fnet= 14.4
now what do i do?

 

[rock.freak667]

When both are in the same direction

Fa+Fb=ma (a = 0.9)

when in opposite directions Fa-Fb=ma, this a is in the second line of the problem

 

[triplel777]

yes so Fa+Fb=14.4 how do i find the value of each one?

 

[rock.freak667]

yes so Fa+Fb=14.4 how do i find the value of each one?

you have


F_a+F_b= constant

and

F_a-F_b= other constant


two equations with two unknowns, solve simultaneously.