Physics
posted by Bryian on .
Please help me with these three questions,they deal with coefficient of friction
1) A car rounds a turn of radius 25m at a speed of 20m/s. Find the coefficient of friction neccessary to keep the car on the road
2) A man is attempting to slide a piece of furniture weighing 750N long a floor. Ifhe exerts a force of 75N along a rope and angle of 35 degrees and the object does not move, what is the minimum value for te coeficient of friction?
3) Consider a block on a plane inclined at an angle of 30 degres. If the block weights 950N, what coefficient of friction is neccessary to hold it stationary?

1) set mv^2/r= mu*mg
solve for mu
2) the vertical component of tension reduces weight.
friciton= mu*(mg75sin35)
horizontalforce= 75*cos35
set them equal, solve for mu.
3) I will be happy to critiqeu your thinking. 
thanks for your time and help, but I do not know what mu stands for

mu: coefficent of friction.

I got 13 for number 1, am I wrong?