Physics Problem: Determining Applied and Normal Forces on a Vertical Window

  • Thread starter Thread starter piper210_355
  • Start date Start date
  • Tags Tags
    Physics
AI Thread Summary
To determine the applied and normal forces on a sponge being pushed up a vertical window, the problem involves calculating forces based on the sponge's mass and the coefficient of kinetic friction. The sponge has a mass of 0.800 kg and experiences a frictional force calculated using the coefficient of kinetic friction, u_k = 0.253. The user attempted to find the frictional force and total vertical force by applying trigonometric functions and equations of motion, but seeks confirmation on their approach. They plan to use the Pythagorean theorem to find the magnitude of the applied force after calculating the vertical forces. The discussion highlights the need for clarification on the correct application of physics principles in solving the problem.
piper210_355
Messages
4
Reaction score
0
Physics prob 2 ... Help needed!

Homework Statement



Like i sayed in my other posts this is probably easy but my teacher doesn't teach us anything so i don't have a clue how to do this. Can someone please explain how to do it?

A window washer pushes a sponge up a vertical window at a constant speed by applying a force. The sponge has a mass of .800 kg, and the coefficient of kinetic friction between the sponge and window is u_k=0.253. Determine the magnitude of the applied force, and the magnitude of the normal force exerted by the window on the sponge.

*There is a 20 degree angle( i put the pic below)

Homework Equations



F(y) = weight of sponge + Frictional force

F(f) = u*F(x)

The Attempt at a Solution



ok so what i did was that i took the sin 70 which if I'm not mistaken should equal F(x).
sin 70=F(x)
.94=F(x)

Then I put this in the equation for frictional force.
F(f)=uF(x)
F(f)=(.253)(.94)
F(f)=.238

After that I put it into the equation for F(y).
F(y)=weight of sponge + F(f)
F(y)=(.8)+(.238)
F(y)=1.048

My plan is to do the pythagorian therum to find the applied force, but I want to make sure i am doing it right so far.
 

Attachments

  • p.bmp
    p.bmp
    292.6 KB · Views: 565
Physics news on Phys.org


F(x) = F * sin(70)

where F is magnitude of the applied force.
 
I multiplied the values first without the error limit. Got 19.38. rounded it off to 2 significant figures since the given data has 2 significant figures. So = 19. For error I used the above formula. It comes out about 1.48. Now my question is. Should I write the answer as 19±1.5 (rounding 1.48 to 2 significant figures) OR should I write it as 19±1. So in short, should the error have same number of significant figures as the mean value or should it have the same number of decimal places as...
Thread 'A cylinder connected to a hanging mass'
Let's declare that for the cylinder, mass = M = 10 kg Radius = R = 4 m For the wall and the floor, Friction coeff = ##\mu## = 0.5 For the hanging mass, mass = m = 11 kg First, we divide the force according to their respective plane (x and y thing, correct me if I'm wrong) and according to which, cylinder or the hanging mass, they're working on. Force on the hanging mass $$mg - T = ma$$ Force(Cylinder) on y $$N_f + f_w - Mg = 0$$ Force(Cylinder) on x $$T + f_f - N_w = Ma$$ There's also...
Back
Top