For some reason i cant seem to get my head around this simple circular motion/ banked road question....
2001 Q6 a:\
A road contains a bend that is part of a circle of radius r. At the bend, the road
is banked at an angle α to the horizontal. A car travels around the bend at
constant speed v. Assume that the car is represented by a point of mass m, and
that the forces acting on the car are the gravitational force mg, a sideways
friction force F (acting down the road as drawn) and a normal reaction N to the
road.
![](/proxy.php?image=http%3A%2F%2Fwww.freeimagehosting.net%2Fuploads%2F6ed01fc05c.jpg&hash=f5761ea4213e41e84bf725a83dff7d92)
Basically i get everything in the answers except resolving the forces horizontally which i thought should be like this(let A=theta):
FCosA + NSinA = -(mv^2)/r
since the net force is directed inwards away from FcosA and NSinA
but the answers say:
FCosA + NSinA = (mv^2)/r , without the negative sign
....please explain
thanks
2001 Q6 a:\
A road contains a bend that is part of a circle of radius r. At the bend, the road
is banked at an angle α to the horizontal. A car travels around the bend at
constant speed v. Assume that the car is represented by a point of mass m, and
that the forces acting on the car are the gravitational force mg, a sideways
friction force F (acting down the road as drawn) and a normal reaction N to the
road.
![](/proxy.php?image=http%3A%2F%2Fwww.freeimagehosting.net%2Fuploads%2F6ed01fc05c.jpg&hash=f5761ea4213e41e84bf725a83dff7d92)
Basically i get everything in the answers except resolving the forces horizontally which i thought should be like this(let A=theta):
FCosA + NSinA = -(mv^2)/r
since the net force is directed inwards away from FcosA and NSinA
but the answers say:
FCosA + NSinA = (mv^2)/r , without the negative sign
....please explain
thanks