Rotational accel to linear accel

In summary, the conversation discusses how to solve for a in a problem involving a sphere rolling down a hill. The solution involves using the condition for rolling without slipping, Newton's 2nd law applied to translation and rotation, and combining equations to get the final answer of a = (5/7)g sin theta.
  • #1
chloechloe
9
0

Homework Statement


I do not understand how a was solved for. the picture is a sphere rolling down a hill. Asked to solve for a.


Homework Equations


solve for a, use alpha = a/r
ma = mg sin theta - fs; T = fs*r = I*alpha = (2/5)mr^2; fs = (2/5)ma
a = (5/7)g sin theta

I can't see the progression through these steps

The Attempt at a Solution

 
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  • #2
chloechloe said:
use alpha = a/r
(1) That's the condition for rolling without slipping.
ma = mg sin theta - fs;
(2) That's Newton's 2nd law applied to translation.
T = fs*r = I*alpha = (2/5)mr^2;
This is an attempt to apply Newton's 2nd law to rotation, but alpha was left out of the right hand term. It should be:
(3) T = fs*r = I*alpha = (2/5)mr^2*alpha
fs = (2/5)ma
(4) Combine 1 and 3 to get this.
a = (5/7)g sin theta
Combine 4 with 2 to get this.
 
  • #3
Thank you. Makes sense now. I was getting stuck at combining things at the end. The missing alpha didn't help either.
 

FAQ: Rotational accel to linear accel

What is rotational acceleration to linear acceleration?

Rotational acceleration to linear acceleration is the conversion of rotational motion to linear motion. It is a measure of the change in velocity of an object moving in a circular path, which can be translated into linear acceleration along a straight line.

How is rotational acceleration to linear acceleration calculated?

The formula for calculating rotational acceleration to linear acceleration is a = r * α, where a is the linear acceleration, r is the radius of the circle, and α is the angular acceleration. This formula is derived from the relationship between the linear and angular velocities of an object in circular motion.

What are some real-world examples of rotational acceleration to linear acceleration?

Examples of rotational acceleration to linear acceleration can be seen in everyday objects such as bicycle wheels, car tires, and spinning tops. In these cases, the rotational motion is converted into linear motion, allowing the objects to move in a straight line.

How is rotational acceleration to linear acceleration related to centripetal force?

Rotational acceleration to linear acceleration is closely related to centripetal force, which is the force that keeps an object moving in a circular path. Centripetal force is directly proportional to the square of the object's linear speed and inversely proportional to the radius of the circular path.

What factors affect rotational acceleration to linear acceleration?

The factors that affect rotational acceleration to linear acceleration include the object's mass, the radius of the circular path, and the angular acceleration. The direction and magnitude of the linear acceleration also depend on the direction and magnitude of the angular acceleration.

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