Help urgent mechanics

Help!
I don’t understand how to do this question… I get the first 2 lines but for the third I don’t get why it’s minus mgsin30 and minus 0.2mgcos30
Why are they both minus when they’re acting in the same direction?

(edited 11 months ago)

Reply 1

Carrotsroom

If you draw the diagram, you'll find that the forces act in the opposite direction when the coin moves up the slide. Also the fact ma is stated as positive means they are taking forces up the slope
Draw your horizontal and vertical forces and you'll be able to see it.
Fiction is also moving against the coin, hence its negative

(edited 11 months ago)

Reply 2

davros

Original post by Alevelhelp.1

If you took "up the slope" as the positive direction, then initially the motion is in the positive direction, but weight and friction are both acting against the motion so they are negative.