Want to verify textbook ans on angular velocity

In summary, we have a 5kg hoop of radius 3m rolling without slipping on a horizontal surface with an initial angular speed of 3 rad/s. It then rolls up a ramp inclined at 20 degrees with the horizontal. Using the equation for total initial energy and equating it to the final energy in terms of mass, gravity, and height, we can find the vertical height to be 4.128 meters. However, to find the distance along the slope, we must also consider the translational kinetic energy, giving us a total distance of 12.1 meters. The textbook's answer of 24 meters appears to be incorrect.
  • #1
tubworld
39
0
I got the following qn:

In a circus performance, a large 5kg hoop of radius 3m rolls without slipping. If the hoop is given an angular speed of 3 rad/s while rolling on the horizontal and allowed to roll up a ramp inclined at 20 degrees with the horizontal, how far(measured along the incline) does the hoop roll?

My solution is as follows:
Total initial energy=0.5 * I * (angular velocity)^2
=0.5 * 45 * 3^2
=202.5
Final energy = mgh
= 5gh, where h is the vertical height
Equating the 2,
202.5=5gh
h=4.128.

Since we want to find the distance along the slope, d, d=h/sin20 = 12.1m

This is the ans I got, but it seems that the back of the textbook ans is 24m . Is the textbook ans correct or wrong?
 
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  • #2
You included the rotational kinetic energy but forgot the translational kinetic energy.
 
  • #3
Thanks! How could i have forgotten that?
 

Related to Want to verify textbook ans on angular velocity

1. What is angular velocity and why is it important in physics?

Angular velocity is a measure of how quickly an object is rotating around an axis. It is important in physics because it helps us understand the motion of objects in circular or rotational motion, which is a common occurrence in many natural phenomena.

2. How is angular velocity calculated?

Angular velocity is calculated as the change in angular displacement over time. This can be represented mathematically as ω = Δθ/Δt, where ω is the angular velocity, Δθ is the change in angular displacement, and Δt is the change in time.

3. How is angular velocity different from linear velocity?

Angular velocity measures the rate of change of angular displacement, whereas linear velocity measures the rate of change of linear displacement. In other words, angular velocity deals with rotational motion while linear velocity deals with straight-line motion.

4. What units is angular velocity measured in?

Angular velocity is typically measured in radians per second (rad/s) or degrees per second (deg/s). However, it can also be measured in revolutions per minute (rpm) or revolutions per second (rps).

5. What factors can affect the angular velocity of an object?

The angular velocity of an object can be affected by its moment of inertia, the torque applied to it, and any external forces acting on it. Additionally, changes in the object's mass, shape, or speed can also affect its angular velocity.

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