Coefficient of kinetic friction and pulling force

[eureka360]

hi everybody.. can i ask how to get a coefficient of kinetic friction if a 20 kilogram sled is being pulled across a horizontal surface at a constant velocity. The pulling force has a magnitude of 80 Newton and is directed at an angle of 30 degrees above the horizontal. please answer my question.. i badly need you help..

 

[gunblaze]

I assume you know the formula for finding kinetic friction. If the sled is moving at constant velocity, what will be the relationship between the horizontal component of the pulling force and the kinetic friction? How do you find the normal force given the weight of the sled and the upward force that the person is helping ease the contact between the sled and the floor.