Pendulum problem-last answer was wrong please

  • Thread starter Thread starter bharp24
  • Start date Start date
  • Tags Tags
    Pendulum
AI Thread Summary
The discussion revolves around a pendulum problem involving a rock of mass 0.12 kg attached to a 0.80 m string, swinging to a maximum angle of 45 degrees. The key questions focus on calculating the speed of the rock at the vertical position and the tension in the string at various angles. The solution emphasizes using conservation of energy, noting that at the lowest point, all energy is kinetic, while at the highest point, it is potential. The original poster confirms they figured out the problem after seeking help. The discussion highlights the importance of energy conservation in solving pendulum dynamics.
bharp24
Messages
14
Reaction score
0
pendulum problem--last answer was wrong..need help please!

A small rock with mass 0.12 is fastened to a massless string with length 0.80 to form a pendulum. The pendulum is swinging so as to make a maximum angle of 45 with the vertical. Air resistance is negligible.

What is the speed of the rock when the string passes through the vertical position?

What is the tension in the string when it makes an angle of with the vertical?

What is the tension in the string as it passes through the vertical?
 
Physics news on Phys.org
For the first question you need to look at conservation of energy. The pendulum is at its lowest point when in the vertical position, so it has no potential energy. Thus all energy must be kinetic. Likewise, when its at the highest position (454 degree angle with vertical), it has no kinetic energy but maximum potential energy.
 
thanks! i figured it out a little bit ago though!
 

Thread 'Errors and significant figures'

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...
View full post »
Thread 'A cylinder connected to a hanging mass'

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...
View full post »

Similar threads

Foucault Pendulum at the North Pole
Replies
9
Views
2K
Work done on a conical pendulum
Replies
3
Views
2K
Tension in string for a bob pendulum
Replies
11
Views
5K
For a Pendulum: Knowing Acceleration Find Maximum Angle
Replies
26
Views
3K
Finding the period of a pendulum in motion along a curve
Replies
8
Views
2K
What is the correct tension equation for a pendulum at rest?
Replies
2
Views
2K
Swinging Tarzan: Solving for Maximum Height & Angle
Replies
3
Views
2K
Rotational Motion of a pendulum
Replies
6
Views
5K
Is the Angular Momentum of a Pendulum Conserved?
Replies
5
Views
6K
Simple Pendulum undergoing harmonic oscillation
Replies
21
Views
3K

Hot Threads

Recent Insights

Back
Top