Circular motion, forces

I’m stuck on an Isaac physics question, I’ve tried this a couple times and keep getting the same answer.

My working out is here,

Also I have watched the hint video and they got a different equation when equating the vertical forces. I have Ncos(30) + mu*Nsin(30) = mg, but they have -mu *Nsin(30). On the diagram they have also drawn the friction force down the slope, but surely it should be up the slope? Super confused. Would appreciate help.

Also here is an image of the hint with a diagram and their starting equations.

...

TSR has problems with attachements sometimes - try uploading to your favourite image hosting site and linking across.

Question asks for the maximum speed. I.e. if it went any faster the car would not make it round the curve. So friction is acting, in general, towards the centre of rotation, and hence down the slope.

Question asks for the maximum speed. I.e. if it went any faster the car would not make it round the curve. So friction is acting, in general, towards the centre of rotation, and hence down the slope.

Tried that, now I’m just getting the same final equation but negative mu * sin 30 on the bottom. This gives me a negative value for the velocity squared?

Tried that, now I’m just getting the same final equation but negative mu * sin 30 on the bottom. This gives me a negative value for the velocity squared?

At a guess you only changed one of your intial equations, but I've no idea as you haven't posted any working!

Do you see my working out now? I can upload to another site and link if not. I have the sane equations as the hint video now

Can see it now. cos30-mu sin 30 is still postive, giving a positive v^2. Does it not?

Can see it now. cos30-mu sin 30 is still postive, giving a positive v^2. Does it not?

Ohhh I’m in radians.