Forces and Friction

[hannahiyo]

what size unbalanced force acts on a mass of 3 kg's which accelerates at 4 m/s squared on a flat surface if a) there is no friction b) there is a friction of 4 newtons

[gen2]

apply f=ma for the frictionless case

if a force of 4N has to be overcome then the force applied has to be that much greater. ie (f+4)=ma

[hannahiyo]

Sorry i am not to sure what you mean.. I know the formula and how it works like the triangles but it really is just what i do with the friction bit do i take it away from the resultant force i found out in A?

[TeeGee]

Should that not be f=ma+4 ? i.e. more f is required to counteract friction

[gen2]

Yes TeeGee, you are right of course - I have added the 4 on the wrong side of the equation.

[hannahiyo]

Thanks every so much for your help it was greatly appreciated