## Force needed to pull a block up an incline.

1. The problem statement, all variables and given/known data
Calculate the force needed to pull a mass of 20 kg at a uniform slow speed up a plane inclined at an angle of 30 with the horizontal if the coefficient of kinetic friction is 0.20.

2. Relevant equations
WN= w cos $$\vartheta$$
WT= w sin $$\vartheta$$
$$\mu$$s= tan$$\vartheta$$

3. The attempt at a solution

I don't even know how to get started.

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 Recognitions: Gold Member Science Advisor Staff Emeritus If the block is moving at a constant speed then you know that there is no net force acting on the block.
 so the friction force is (.2)(20)(9.8)(cos 30) ? and the gravitational force is (20)(9.8)(sin 30) ? i got 34 N for friction and 98 N for gravitational. are they supposed to equal zero? or do i add them together to find the force i need to overcome? or could i just overcome the strongest?

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## Force needed to pull a block up an incline.

So what force is needed to make them balance?

 okay, so 34 N for friction pull the box up the slope, and 98 N gravity pull down. 98 N - 34 N = 64 N needed to equalize them, and more than 64 to make it move uphill?
 Recognitions: Gold Member Science Advisor Staff Emeritus What direction will the friction be acting in if the box is being pulled up the slope?
 Recognitions: Homework Help What is the direction of the force applied and whether the friction will depend on that direction.
 Recognitions: Homework Help If the minimum force needed is required than the force must be applied at an angle equal to angle of friction [tan^-1 (u)] with the incline.