You're using a rope to pull a sled at constant velocity across level snow,with coefficient of kinetic friction 0.050 between sled and the snow. The sled is loaded with physics books, giving a total mass of 31kg.
What is the force when at 30 degrees above the horizontal?

Question

You're using a rope to pull a sled at constant velocity across level snow,with coefficient of kinetic friction 0.050 between sled and the snow. The sled is loaded with physics books, giving a total mass of 31kg. 
What is the force when at 30 degrees above the horizontal?

anonymous · Answer

Break the force down into its components. The y component is going to lift up on the sled, thereby reducing the normal force. The velocity is constant, so acceleration is zero.|dw:1348200931373:dw|
Use the lessened normal force to calculate friction.

anonymous · Answer

Just for clarity, that's force of gravity *minus* the upward component of the rope pulling.