When a bird flies into a bar; solving for angular velocity

AI Thread Summary
The problem involves a 550g bird colliding with a stationary vertical bar, which is 0.73m long and has a mass of 2.20kg. The bird strikes the bar 25cm below the top while flying at 2.20m/s, leading to a calculation of the bar's angular velocity immediately after the impact. The correct angular velocity after the collision is determined to be 1.486 rad/s. The discussion highlights the importance of correctly applying the equations for kinetic energy and moment of inertia to solve for angular velocity. Understanding the dynamics of the collision is crucial for accurately determining the bar's motion post-impact.
tylertwh
Messages
22
Reaction score
0

Homework Statement



A 550.0g bird is flying horizontally at 2.20m/s , not paying much attention, when it suddenly flies into a stationary vertical bar, hitting it 25.0cm below the top. The bar is uniform, 0.730m long, has a mass of 2.20kg , and is hinged at its base. The collision stuns the bird so that it just drops to the ground afterward (but soon recovers to fly happily away).

0.55 kg = mass of bird
2.2 m/s = velocity of bird
0.48 m = distance from axis of rotation bird hits bar
0.73 m = length of bar
2.2 kg = mass of bar

A)What is the angular velocity of the bar just after it is hit by the bird?

B)What is the angular velocity of the bar just as it reaches the ground?

Homework Equations



KE(bird) = (1/2)mv2
KE(bar) = (1/2)Iω2
I(bar) = (1/3)mr2

The Attempt at a Solution



(1/2)mv2 = (1/6)mr2ω2
ω = 2.75
INCORRECT

For part B I can't solve until I have the answer to part A
 
Physics news on Phys.org
I found my mistake for part A.

The answer to part A is 1.486
 
Kindly see the attached pdf. My attempt to solve it, is in it. I'm wondering if my solution is right. My idea is this: At any point of time, the ball may be assumed to be at an incline which is at an angle of θ(kindly see both the pics in the pdf file). The value of θ will continuously change and so will the value of friction. I'm not able to figure out, why my solution is wrong, if it is wrong .
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...
Back
Top