What is the direction of acceleration and friction in this friction problem?

  • Thread starter Thread starter srh
  • Start date Start date
  • Tags Tags
    Friction
AI Thread Summary
The discussion focuses on determining the friction force acting on a block at a 30-degree angle with a force P of 200 N. The user created a free-body diagram and calculated the normal force as 966.025 N and the friction force as 326.79 N, but expressed concern about the friction value not fitting the inequality f ≤ usN. Participants suggested clarifying the direction of acceleration and friction to correctly establish the coordinate system for the forces. Overall, the conversation emphasizes the importance of accurately representing forces in a diagram to solve the problem effectively.
srh
Messages
7
Reaction score
0

Homework Statement


I have attached a picture. Determine the friction force acting on the block shown when the angle is 30 degrees and P=200 N.


Homework Equations


us=0.3 (static friction)
uk=0.2 (kinetic friction)


The Attempt at a Solution



I set up a free-body diagram w/the 1kN, P, Normal force and frictional force. I was able to solve for both the Normal force and frictional force. I got 326.79N for friction and 966.025 for Normal. I thought I was incorrect because it doesn't fit into the f<=usN
 

Attachments

  • physics.JPG
    physics.JPG
    5 KB · Views: 414
Physics news on Phys.org
Perhaps if you showed your working, we could show you where you've gone wrong...
 
I would draw a better diagram :).

One with acceleration; in which direction is it pointing? Acceleration sets your positives/negatives on the axis on the diagram. The friction; in which way is friction pointing/acting?

After doing such you can do a summination of forces =).
 
TL;DR Summary: I came across this question from a Sri Lankan A-level textbook. Question - An ice cube with a length of 10 cm is immersed in water at 0 °C. An observer observes the ice cube from the water, and it seems to be 7.75 cm long. If the refractive index of water is 4/3, find the height of the ice cube immersed in the water. I could not understand how the apparent height of the ice cube in the water depends on the height of the ice cube immersed in the water. Does anyone have an...
Thread 'Variable mass system : water sprayed into a moving container'
Starting with the mass considerations #m(t)# is mass of water #M_{c}# mass of container and #M(t)# mass of total system $$M(t) = M_{C} + m(t)$$ $$\Rightarrow \frac{dM(t)}{dt} = \frac{dm(t)}{dt}$$ $$P_i = Mv + u \, dm$$ $$P_f = (M + dm)(v + dv)$$ $$\Delta P = M \, dv + (v - u) \, dm$$ $$F = \frac{dP}{dt} = M \frac{dv}{dt} + (v - u) \frac{dm}{dt}$$ $$F = u \frac{dm}{dt} = \rho A u^2$$ from conservation of momentum , the cannon recoils with the same force which it applies. $$\quad \frac{dm}{dt}...
Back
Top