Jawapan

2014-07-01T13:42:17+08:00
I would think the answer is D!

Firstly, remember that friction ALWAYS opposes the stronger force (or direction of motion). It always helps the weaker force ;)

Then you try to find the net force by subtracting around. Take note of D, it's tricky! But again, remember that friction opposes direction of motion. Since the net force of D is negative (negative acceleration), so the block is decelerating.