Photo of rotating scale and falling coins

In summary, the conversation discusses a problem involving coins on a scale and the application of Newton's laws of motion. It is determined that the coin closest to the pivot point will remain on the scale, while others farther away will fall off. This is represented in option (B) of the given diagrams. The solution also involves calculating torque and acceleration using relevant equations.
  • #1
Pushoam
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51

Homework Statement


upload_2017-12-31_12-57-32.png


Homework Equations

The Attempt at a Solution


The option (a) says that the 1st coin remains at its earlier position. Due to gravitational force, the 1st coin falls down, hence option (a) is wrong.

I don’t understand the difference between option (B) and (C).

In my opinion, both option says that all of the coins which have left the scale falls down having same position vector.

I am not being able to apply Newton's laws of motion here.
 

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  • #2
Please complete the template and provide the statement of the problem and the relevant equations.
 
  • #3
kuruman said:
Please complete the template and provide the statement of the problem and the relevant equations.
The forces acting on the coin after leaving the scale is m ## \vec g ## .

The torque on the scale about the fixed end is

## mg \frac 1 2 L = \frac { mL^2} 3 \alpha ##

## \alpha = \frac { 3g } {2L} ##

that part of the scale ( which is at a distance L' > ## \frac { 2L} 3 ## from the pivot ) has an acceleration magnitude ## \geq g ## .

So, the coins at a distance L' > ## \frac { 2L} 3 ## will leave the scale, while the rest of the coin will remain on the scale. Hence, the answer is option (B).

Is this correct?
 
  • #4
Pushoam said:
The option (a) says that the 1st coin remains at its earlier position.
As I read diagrams a to c, they all show the leftmost coins still on the scale, with the rightmost forming a horizontalline below the initial position. They only differ in where the bend in the line is. Yes, diagram a) has the bend very near the left, but not quite.
So you need to solve the problem analytically to find whereabouts the bend shpuld be, then see which diagram looks closest.
Pushoam said:
I am not being able to apply Newton's laws of motion here.
Why not? Try to determine the initial angular acceleration of the scale.
 
  • #5
haruspex said:
Why not? Try to determine the initial angular acceleration of the scale.
Please see the post # 2.
 
  • #6
Pushoam said:
The forces acting on the coin after leaving the scale is m ## \vec g ## .

The torque on the scale about the fixed end is

## mg \frac 1 2 L = \frac { mL^2} 3 \alpha ##

## \alpha = \frac { 3g } {2L} ##

that part of the scale ( which is at a distance L' > ## \frac { 2L} 3 ## from the pivot ) has an acceleration magnitude ## \geq g ## .

So, the coins at a distance L' > ## \frac { 2L} 3 ## will leave the scale, while the rest of the coin will remain on the scale. Hence, the answer is option (B).

Is this correct?
Looks good.
 
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What is the purpose of the photo?

The purpose of the photo is to capture the motion and weight distribution of the falling coins as they rotate on a scale. It allows for the visualization and analysis of the physics behind the motion.

How does the scale measure the weight of the coins?

The scale uses the force of gravity to measure the weight of the coins. As the coins fall, they exert a force on the scale, causing it to register a weight measurement.

What factors affect the motion of the coins?

The motion of the coins is affected by several factors, including gravity, air resistance, and the shape and weight of the coins. The rotation of the scale also plays a role in the motion of the coins.

Can the photo be used to calculate the weight of the coins?

Yes, the photo can be used to calculate the weight of the coins by analyzing the motion and forces involved. This can be done using equations from Newton's laws of motion and principles of rotational motion.

How can this photo be used in scientific research?

This photo can be used in scientific research to study the principles of motion and forces, as well as to analyze the properties of the coins such as their weight and shape. It can also be used to test the accuracy of various theories and equations.

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