Standard mech Q

1. Jan 16, 2006

discombobulated

hi this is a simple question but for some reason it's not clicking.

A ball of mass 0.5kg is pulled across a smooth horizontal floor by a horizontal string attached to the dog. The tension in the string is 0.75N. Calculate the acceleration produced. Given the ball starts from rest, determine how far it will move in 2 seconds.

I know how to do the second part but some help would be appreciated on the first bit please.

F resultant = F - T
F-0.75 = ma
a = F- 0.75 /0.5
errm...and then?

2. Jan 16, 2006

Homer Simpson

Is the ball rolling? or is it dragging across the floor? Some coeffeciant of friction would be needed if it was being dragged.

3. Jan 16, 2006

discombobulated

oops sorry i didn't read the question properly, it's actually a bag and it's being pulled across.

4. Jan 16, 2006

Staff: Mentor

Since the floor is smooth, I would assume that the only horizontal force acting on the bag is the tension in the string, which is given.

5. Jan 16, 2006

discombobulated

Of course, because then the acceleration = 1.5 which is correct.

Thanks!