How can I solve this physics problem step by step?

In summary, the task is from a physics competition and it appears as though the poster is having some difficulty solving it. They mention that they have forgotten the hanging mass and need to find how much force is needed to push the incline so that the roller is at rest. They also mention that their equation is dimensionally incorrect. They also give some advice on how to improve their work.
  • #1
Frouel
8
0
Homework Statement
Consider the layout shown in the figure. ˙
A roller with a mass m_w and radius and moment inertia about the axis of rotational symmetry
I = ((m_w)R^2)/2 rolls without slippage and without rolling friction on an inclined plane (with an angle of inclination α) parts of the block, and the block of mass m_k moves without friction on the stationary table. The mass of the weight is m_c.
a) for the data m_k, m_c, R, α determine the mass of the cylinder
m_w, at which the cylinder can rest relative
block demo;
b) for the data m_w, m_k, R, α, determine the mass of the mass m_c at which the block may rest
to the table;
c) for (any) data m_k, R, m_w, α and
block acceleration a_k find the mass of the weight
m_c.
The acceleration due to gravity is g
Relevant Equations
a = gsina.
I = ((m_w)R^2)/2
a = m_c*g/(m_c+m_k+m_w)
I attended to many attemps and I not able to find out no dependencies in this layout. Does someone can show me how to solve this problem step by step? What we must take into considarion in solving such tasks?. How to start?. I got stuck.
This task is from Polish Physics Olympics.

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  • #2
I don't think you will find (m)any people here willing to show you how to solve this step by step because it is against forum rules. Please read them. Nevertheless, I will tell you where I would start. I would forget the hanging mass and find how much force is needed to push on the incline so that the roller is at rest relative to it. Then I would consider that this force comes from the tension in the string.

Also, please be considerate to those who read your posts. Although you fulfilled the letter of the law and posted your attempt, it is very difficult to decipher what you did. I have no doubt that if you submitted this to the Olympics referees, it would not get much traction. I strongly recommend that you use LaTeX (click on "LaTeX guide" above "Attach files") on the lower left to see how it is done. I also recommend that you specify with words what all the variables that you use stand for.
 
Last edited:
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Likes phinds
  • #3
Your equation starting ##\sin(\alpha)=## is dimensionally incorrect. You forgot to square root. But you'd do better to work with tan, not sin.

Further to @kuruman's comments and advice...
It is going to be tough commenting on specific sections of your work. Per forum rules, images are for diagrams and textbook extracts. Your working should be typed in. If you must post images of algebra, number every equation.

It also helps to include some explanation of how you get your equations, e.g. "horizontal forces and acceleration of ... in the reference frame of ...".
 

Related to How can I solve this physics problem step by step?

1. What is an incline?

An incline is a sloped surface, typically used in physics experiments to study the effects of gravity on objects.

2. How does mass affect an object on an incline?

The mass of an object affects its acceleration on an incline. The greater the mass, the more force is required to move the object up the incline.

3. What is the relationship between incline angle and speed?

The steeper the incline, the faster an object will accelerate down the incline. This is due to the increased force of gravity acting on the object.

4. How does friction impact an object on an incline?

Friction acts against the motion of an object on an incline, causing it to slow down. The amount of friction depends on the surface of the incline and the object's mass.

5. How can I calculate the speed of an object on an incline?

The speed of an object on an incline can be calculated using the equation v = √(2ghsinθ), where v is the speed, g is the acceleration due to gravity, h is the height of the incline, and θ is the angle of the incline.

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