Solving a Tension Problem with 9 kg Handing Weight & 5 kg Block

  • Thread starter Thread starter tristan_fc
  • Start date Start date
  • Tags Tags
    Tension
AI Thread Summary
The discussion revolves around solving a tension problem involving a 9 kg hanging weight and a 5 kg block on a table, with a coefficient of kinetic friction of 0.187. The original poster is confused about how to calculate the tension in the string, mistakenly believing that friction increases tension. However, it is clarified that if there were no friction, the block would move freely, resulting in no tension in the rope. The correct understanding is that the tension in the rope is equal to the friction force opposing the motion of the block. The conversation emphasizes the importance of accurately accounting for forces in tension problems.
tristan_fc
Messages
12
Reaction score
0
I believe that I was late the day my instructor explained this type of problem in class, and my textbook is worthless, so I thought I would give this a shot. It's just a tension problem, but I don't know for sure how to do it.

A 9.00 kg handing weight is connected by a string over a pulley to a 5.00 kg block that is sliding on a flat table. If the coefficient of kinetic friction is 0.187, find the tension in the string.

I believe that tension is the sum of all forces on the rope correct? I recall my teacher saying that we could turn a similar problem into a problem on the X-axis by making gravity a force pulling on the block in the x-direction. Anyway, I thought that I would just do 9*9.8+-(5*0.187), but that didn't seem right to me because it would seem that a frictional force would increase the tension and not decrease it? I appreciate any help.

-Tristan
 
Physics news on Phys.org
eh... I posted my question in the wrong section and they moved it here. I'm actually in Engineering Physics I in college, but I guess it doesn't matter where the question is if I get help.
 
Yes, frictional force would increase tension, not decrease it.
However, if there were NO friction force, there would be NO tension on the rope, not the "9*9.9" you have. If there were no friction force the block would move freely. The tension on the rope IS the friction force.
 
Thread 'Variable mass system : water sprayed into a moving container'

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}...
View full post »

Thread 'Egg Drop Challenge! Need ideas for winning designs'

I was thinking using 2 purple mattress samples, and taping them together, I do want other ideas though, the main guidelines are; Must have a volume LESS than 1600 cubic centimeters, and CAN'T exceed 25 cm in ANY direction. Must be LESS than 1 kg. NO parachutes. NO glue or Tape can touch the egg. MUST be able to take egg out in less than 1 minute. Grade A large eggs will be used.
View full post »

Similar threads

Tension in a string connecting two blocks having equal and opposite velocities
Replies
21
Views
371
Rocket + Connected Body Dynamics problem
Replies
47
Views
3K
Pulley with friction, how to get the friction in the pulley?
Replies
23
Views
2K
Help again in interpreting a pulley with a spring and a block
2
Replies
52
Views
3K
Is it friction or tension acting on the person hanging on a rope?
Replies
4
Views
1K
Force pulling on a string at an angle with a block at the other end
Replies
2
Views
1K
Why are the forces on torque tension and not the weight of the mass?
Replies
7
Views
1K
Plotting the graph of Friction Force vs. time (Laws of motion)
Replies
1
Views
2K
Why is the tension force equal to friction force
Replies
9
Views
7K
Newton's law problem: Pushing 2 stacked blocks on a horizontal table
Replies
13
Views
3K

Hot Threads

Recent Insights

Back
Top