Rotational Motion FInding the total ENergy

In summary, a ball with a radius of 2.5 cm, a mass of .125, and a speed of .547 m/s is rolling across a table 1.04 m off the ground. It then rolls down a ramp. Using equations for gravitational potential energy, linear kinetic energy, elastic potential energy, and rotational kinetic energy, the final velocity of the ball is determined to be approximately 3.85 m/s, assuming energy is conserved.
  • #1
Schu
12
0
Particulars:
ball has a radius of 2.5 cm a mass of .125 and is rolling across a table with a speed of .547 m/s, this table is 1.04 m off the ground. It rolls to the edge and down a ramp How fast will it be rolling across the floor?

First I found the Gravitational Potential Energy: Ep=mgh
Initial of 1.2753 FInal = 0

THen the Linear Kinetic ENergy : 1/2 mv^2
Initial .0187005625 FInal .0625v^2

Elastic Potential Energy: .5k(delta)x^2
0 0

Rotational Kinetic Energy: 1/5mv^2
initial .007480225 FInal .025v^2

Now I need to bring them all togther and solve the final velocity.

Is the Sum of the inital energy's = to the SUM of the final energy's?
If that's true then 1.30148075 = .0875v^2
so v = 3.85 m/s
Is that at all right??
:confused:
 
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  • #2
I need help ASAP

Is anyone out there?

I would appreciate the help :confused:
 
  • #3
Looks ok to me. (I got 3.86 m/s, by rounding off)
 
  • #4
rotational KE

I didn't check your arithmetic, but I have some comments.
Schu said:
Rotational Kinetic Energy: 1/5mv^2
The rotational KE is [itex]{KE}_{rot} = 1/2 I \omega^2[/itex].

You will also need the "rolling condition": [itex]V = \omega R[/itex].
Is the Sum of the inital energy's = to the SUM of the final energy's?
Yes, if you assume energy is conserved, which seems reasonable for this problem.
 

1. What is rotational motion?

Rotational motion is the movement of an object around an axis or center point.

2. How is rotational motion different from linear motion?

Rotational motion involves an object rotating around an axis, while linear motion involves an object moving in a straight line.

3. How do you calculate the total energy in rotational motion?

The total energy in rotational motion is calculated by adding the kinetic energy of rotation (1/2*I*w^2) and the potential energy of rotation (mgh) together.

4. What is the difference between angular velocity and linear velocity?

Angular velocity is the rate at which an object rotates around an axis, while linear velocity is the rate at which an object moves in a straight line.

5. How does the moment of inertia affect rotational energy?

The moment of inertia, which is a measure of an object's resistance to change in rotational motion, affects the amount of rotational energy an object has. Objects with a larger moment of inertia will require more energy to rotate at a certain speed compared to objects with a smaller moment of inertia.

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