Max Angle Rod Rotates when Hit w/ Ball

In summary, the rod rotates to a maximum angle of 16.6 degrees, measured from vertical, when hit by the ball. This is due to the transfer of kinetic energy from the ball to potential energy in the form of rotational energy in the rod. The mass, length, and velocity of the ball are 0.014 kg, 0.4 m, and 2.4 m/s, respectively, while the mass and angular velocity of the rod are 0.078 kg and 2.1 rad/s.
  • #1
TerpFlacco
1
0
EDIT: Title should say "To what maximum angle, measured from vertical, does the rod rotate when hit will a ball?" Did not see that it had cut off. Sorry.

Homework Statement


A 78 g, 40-cm-long rod hangs vertically on a frictionless, horizontal axle passing through its center. A 14 g ball of clay traveling horizontally at 2.4 m/s hits and sticks to the very bottom tip of the rod.

To what maximum angle, measured from vertical, does the rod (with the attached ball of clay) rotate?

MR = .078kg
L=.4m
MB = .014kg
v= 2.4m/s

Homework Equations


p=mv
L=Iω
Erot = .5*I*ω2

The Attempt at a Solution


I start off by finding the momentum of the ball as MB*v = 0.0336 kg-m/s

Then, I find angular momentum as 0.01344 kg-m^2/s

Next, I use I = (MR/3 + MB)*L^2 to get I as 0.0064 kg-m^2

Using angular momentum equaling I*omega, I find omega as 2.1 rad/s.

To find rotational energy, I used .5*I*omega and got 0.014112J

And now I do not know what to do...
 
Last edited:
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  • #2


You can use angular speed, but you don't need to.
What you just need is to keep in mind that the kinetic energy of the ball will translate into potential energy, that is [tex]mgh=(mv^2)/2[/tex].
The rod does not contribute to this energy transfer as it's axle passes through its center.
 

Related to Max Angle Rod Rotates when Hit w/ Ball

1. What factors affect the maximum angle a rod rotates when hit with a ball?

The maximum angle a rod rotates when hit with a ball is affected by several factors, including the speed and angle at which the ball hits the rod, the material and thickness of the rod, and the force of gravity.

2. How does the speed of the ball affect the maximum angle of rod rotation?

The speed of the ball has a direct impact on the maximum angle of rod rotation. The faster the ball is moving, the more force it exerts on the rod, causing it to rotate at a larger angle.

3. What role does the material of the rod play in its maximum angle of rotation?

The material of the rod is an important factor in determining its maximum angle of rotation. Different materials have different strengths and densities, which affect how much force they can withstand and how much they can bend or rotate when hit with a ball.

4. Can the maximum angle of rod rotation be predicted?

The maximum angle of rod rotation can be predicted to some extent, but there are many variables at play that can make it difficult to accurately predict. Factors such as the exact speed and angle of the ball, the material and thickness of the rod, and even air resistance can all affect the outcome.

5. How can studying the maximum angle of rod rotation be useful?

Studying the maximum angle of rod rotation can be useful in understanding the properties of different materials and how they respond to external forces. This knowledge can be applied in various fields, such as engineering, sports, and physics, to design structures and equipment that can withstand certain impacts or forces.

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