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I hate mechanics- giving me a headache!
This question is so elementary, I'm quite embarrassed asking this question, but please help!

A particle of mass 2kg is released from rest and slides 8m down a smooth plane inclined at $30^{\circ}$ to the horizontal. There is a constant resistance force of 4N.

i. Find the work done by the resistance force.

I've drawn the diagram etc and I don't appear to get the answer that is in the book.

My workings are thus followed:

Work done = 4sin30 x 8
Work done =16

Where's the mistake- please help!

The answer in the book is 32.


Thank you!

Friction is acting parallel to the plane thus work done = FdX = 8 x 4 = 32m

Why the sin 30? It's acting paralel to the plane not at any angle to it

Consider F = ma to find the acceleration, and use that to find final velocity

once you have that, you should be able to find GPE (using trigonometry) and the Final KE (Using your value of v)

Then consider this formula

Initial(KE + PE) - Work Done by system = Final(KE + PE)

Thanks for this! I think I need to use this for the next question! :P

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