Solving Forces with Pulleys: 420N & 190N Blocks

  • Thread starter Thread starter rwofford
  • Start date Start date
  • Tags Tags
    Forces Pulleys
AI Thread Summary
The problem involves two blocks connected by a string over a massless pulley, with one block (m1) weighing 420 N on a horizontal surface and the other block (m2) weighing 190 N hanging vertically. The key to solving for acceleration and tension is to analyze the forces acting on each block separately, treating horizontal and vertical components independently. For m1, the relevant forces are the normal force, tension, and gravitational force, while for m2, only the tension and gravitational force are considered. The user is struggling to find a solution due to incorrectly combining horizontal and vertical forces. Properly separating the forces for each block will lead to the correct equations for acceleration and tension.
rwofford
Messages
22
Reaction score
0
so i have this problem with a block sitting on a horizontal surface and this block(m1) has the weight of 420 N. This block is connected by a string to a pulley and then connects to another block(m2) that is hanging from the pulley. The weight of the hanging block is 190 N. Ignore all frictional effects, and assume the pulley to be massless. I have to find the acceleration adn tension.

For this problem i know the free body diagrams..and i also know that the tension asn acceleration will be the same for both blocks. I have tried solving using the net forces but can't come up with an answer...

I have used:

sumF(m1)=Fn+Ft-Fg
sumF=ma
so: Fn+Ft-Fg=ma

sumF(m2)=Ft
sumF=ma
so: Ft=ma

but when i try to solve i am not getting an answer...please help!
 
Physics news on Phys.org
someone please help!
 
...hello?
 
rwofford said:
I have used:

sumF(m1)=Fn+Ft-Fg
sumF=ma
so: Fn+Ft-Fg=ma

sumF(m2)=Ft
sumF=ma
so: Ft=ma

but when i try to solve i am not getting an answer...please help!
Realize that you can't just add horizontal and vertical forces (like Fn and Ft on m1). Treat horizontal and vertical components separately.

m1 accelerates horizontally, so analyze the horizontal forces acting on m1. Similarly, m2 accelerates vertically, so analyze the vertical forces acting on m2.
 
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