Solving Tetherball Problem: Find Tension & Angle θ

  • Thread starter Thread starter ybgl
  • Start date Start date
AI Thread Summary
The discussion revolves around solving a physics problem involving a 0.3 kg ball attached to a 50 cm string, completing two circles per second. Participants suggest using two equations related to tension and gravitational force, specifically Ftcosθ = Mg and mv²/r = ftsinθ. The challenge lies in determining the radius and angle θ, as the radius is dependent on θ, complicating the solution. Suggestions include substituting expressions for radius and using the period to find velocity. The conversation emphasizes the need for algebraic manipulation to resolve the equations effectively.
ybgl
Messages
2
Reaction score
0

Homework Statement


A .3 kg ball is attached to a string that is 50.0 cm in length, and completes 2 circles every second. Find the tension required to whirl the ball with the given constraints and also find the angle θ

2. The attempt at a solution
I only have that Ftcosθ = Mg and that mv^2/r = ftsinθ
I don't know where to go from there since all I have is the length and mass because to find the radius it is r=Lsinθ which I cannot find without θ...
 
Physics news on Phys.org
ybgl said:

Homework Statement


A .3 kg ball is attached to a string that is 50.0 cm in length, and completes 2 circles every second. Find the tension required to whirl the ball with the given constraints and also find the angle θ

2. The attempt at a solution
I only have that Ftcosθ = Mg and that mv^2/r = ftsinθ
I don't know where to go from there since all I have is the length and mass because to find the radius it is r=Lsinθ which I cannot find without θ...
Welcome to PF!

This is just an algebra problem now. You have done the physics!

2 equations. 2 unknowns. Solve. Hint: try dividing the two equations.

AM
 
Last edited:
I have tried, it gives me (g)(r)sinθ/cosθ=v^2 which is 3 unknowns since I don't know radius, velocity, or θ
 
ybgl said:
I have tried, it gives me (g)(r)sinθ/cosθ=v^2 which is 3 unknowns since I don't know radius, velocity, or θ
You can work out r from L and θ. θ is the downward angle that the tether makes as measured from the horizontal, so r = Lcosθ. Just substitute into your equation.

v can be determined from the period and radius. Or you can just use mω2r for centripetal force.

AM
 
Andrew Mason said:
You can work out r from L and θ. θ is the downward angle that the tether makes as measured from the horizontal, so r = Lcosθ. Just substitute into your equation.

v can be determined from the period and radius. Or you can just use mω2r for centripetal force.

AM
And where do the solution go from here .Kind of stuck somewhere
 
Welcome to PF, @Lesleyanne :smile:

This thread is over 8 years old, so it's best if you start a new thread here in the Homework Help, Introductory Physics forum and show your work on your problem. That's the best way to get tutorial help with your schoolwork here. Thanks.
 

Thread 'Struggling to understand the concept of this question (ice cube in water optics question)'

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...
View full post »
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 »

Similar threads

Rotational Equilibrium Question
Replies
2
Views
2K
Angle of deviation from a magnetic field
Replies
5
Views
2K
For a Pendulum: Knowing Acceleration Find Maximum Angle
Replies
26
Views
3K
Tension and Uniform Circular Motion (no r, ω, θ)
Replies
7
Views
2K
Finding the speed's dependence on angle θ
Replies
15
Views
2K
Tension in a deformed cylindrical bag on a surface
Replies
18
Views
1K
Maximum angle reached by a cube placed inside a spinning cylinder
Replies
22
Views
2K
Determine the speed and tension of keys swinging in a circular path
Replies
8
Views
2K
Tangential Acceleration/Tension
Replies
6
Views
2K
Tension and net torque in a cable
Replies
10
Views
5K

Hot Threads

Recent Insights

Back
Top