Problem finding angular velocity

In summary, the problem involves a uniform disk with a force of 1.45 lb acting downwards on a string at its center. The disk is initially at rest and has a radius of 0.470 ft. The goal is to determine the angular velocity after 4.45 seconds. The correct equation to use is angvelfinal = angvelinitial + a*t, but the difficulty lies in relating the force to acceleration. After several attempts and two days of work, it was discovered that the calculations were correct, but there was an error in the numbers used. The issue was resolved and the problem was successfully solved.
  • #1
Coletrain12
16
0
[SOLVED] Problem finding angular velocity... !

Homework Statement




The 9.65 lb uniform disk is pin supported at its center and is acted upon by a constant force of P = 1.45 lb as shown. The system starts from rest. Radius of disk is .470 ft

The force P is going straight down from the disk and would spin the disk in a clockwise direction. The force P is at the end of a string.. making the disk spin.

Determine the angular velocity after 4.45 seconds. (rad/s, +CCW)

Homework Equations



I know this problem involves a constant accel equation. I believe the right one is angvelfinal = angvelinitial + a*t



The Attempt at a Solution



The issue i have is that i can't figure out how to relate the force acting on the disk to turn it into acceleration. I have tried setting "Force*Radius=(.5*Mass*radius^2)angaccel" and solving for angaccel and then multiplying it by the time in order to get my angvel but i am having no luck. Any help i appreciated.
 
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  • #2
any other info i need to give guys?? i have been on this question for two days lol. I can finish it i just can't figure out how i get from a force in lbs pulling down on a string turning a disc... to the acceleration of the disc. I've looked through formulas and have had no luck anywhere.
 
  • #3
thanks guys, i figured it out. I was doing it right but somehow my numbers were off somewhere.
 

1. What is angular velocity and how is it different from linear velocity?

Angular velocity is the rate at which an object rotates or moves around a fixed axis. It is different from linear velocity, which measures the rate of change of an object's position in a straight line. Angular velocity is measured in radians per second, while linear velocity is measured in meters per second.

2. How do you calculate angular velocity?

Angular velocity is calculated by dividing the change in angle (in radians) by the change in time. The formula is: angular velocity = change in angle / change in time.

3. What factors affect angular velocity?

The factors that affect angular velocity include the radius of the object's rotation, the mass of the object, and the force applied to the object.

4. How is angular velocity used in real-life applications?

Angular velocity is used in many real-life applications, including engineering, robotics, and sports. In engineering, it is used to calculate the speed and acceleration of rotating parts in machines. In robotics, it is used to control the movement of robotic arms and joints. In sports, it is used to analyze the movements of athletes in activities such as throwing, jumping, and spinning.

5. What are some common problems encountered when finding angular velocity?

Some common problems encountered when finding angular velocity include not knowing the correct formula to use, not having accurate measurements of the angle or time, and not taking into account external forces that may affect the object's rotation. It is important to double-check calculations and consider all relevant factors to ensure an accurate result.

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