
#1
Sep3009, 03:13 PM

P: 14

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 W_{N}= w cos [tex]\vartheta[/tex] W_{T}= w sin [tex]\vartheta[/tex] [tex]\mu[/tex]_{s}= tan[tex]\vartheta[/tex] 3. The attempt at a solution I don't even know how to get started. 



#2
Sep3009, 07:38 PM

Emeritus
Sci Advisor
PF Gold
P: 4,975

If the block is moving at a constant speed then you know that there is no net force acting on the block.




#3
Sep3009, 08:56 PM

P: 14

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? 



#4
Oct109, 05:31 AM

Emeritus
Sci Advisor
PF Gold
P: 4,975

Force needed to pull a block up an incline.
So what force is needed to make them balance?




#5
Oct109, 08:26 AM

P: 14

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? 



#6
Oct209, 07:22 AM

Emeritus
Sci Advisor
PF Gold
P: 4,975

What direction will the friction be acting in if the box is being pulled up the slope?




#7
Oct209, 07:49 AM

HW Helper
P: 508

What is the direction of the force applied and whether the friction will depend on that direction.




#8
Oct209, 07:57 AM

HW Helper
P: 508

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.



Register to reply 
Related Discussions  
block on incline with vertical force  Introductory Physics Homework  10  
Block sliding down an incline and hitting a smaller block  Introductory Physics Homework  7  
A 2.5 kg block and a 3.1 kg block slide down a 30 degree incline.  Introductory Physics Homework  10  
Force needed to keep block from moving on frictionless triangular block  Introductory Physics Homework  1  
force needed to push box down incline plane  Introductory Physics Homework  3 