Angular momentum/ energy conservation.

In summary, the conversation involves a question about a block of mass being suspended by a string and the amount of energy dissipated as it travels a certain distance. The equation mgh=1/2mv^2+mg(h final)+1/2iw^2+L(energy loss) is set up to solve for this, but there is confusion as to why it does not work correctly. The figures are needed to further understand the problem.
  • #1
Roland of G
3
0

Homework Statement


A block of mass 7.00×10-1kg is suspended by a string which is wrapped so that it is at a radius of 6.00×10-2m from the center of a pulley. The moment of inertia of the pulley is 5.70×10-3kg*m2. There is friction as the pulley turns. The block starts from rest, and its speed after it has traveled downwards a distance of D=0.790m is 1.233m/s. Calculate the amount of energy dissipated up to that point.
I set up an equation like this:
mgh=1/2mv^2+mg(h final)+1/2iw^2+L(energy loss) This makes sense to me... Why does this not work correctly?


Homework Equations





The Attempt at a Solution


mgh=1/2mv^2+mg(h final)+1/2iw^2+L(energy loss) This makes sense to me... Why does this not work correctly?
 
Physics news on Phys.org
  • #2
Welcome to PF!

Hi Roland of G! Welcome to PF! :smile:

(have an omega: ω and try using the X2 icon just above the Reply box :wink:)
Roland of G said:
mgh=1/2mv^2+mg(h final)+1/2iw^2+L(energy loss) This makes sense to me... Why does this not work correctly?

It should work. :confused:

Show us the figures. :smile:
 

FAQ: Angular momentum/ energy conservation.

What is angular momentum?

Angular momentum is a property of a rotating object that describes its tendency to keep rotating. It is a vector quantity, meaning it has both magnitude and direction, and is defined as the product of an object's moment of inertia and its angular velocity.

How is angular momentum conserved?

Angular momentum is conserved in a closed system, meaning that the total angular momentum of the system remains constant over time. This means that if there are no external torques acting on the system, the initial angular momentum will be equal to the final angular momentum.

What is the relationship between angular momentum and energy conservation?

Angular momentum and energy conservation are closely related in the sense that they both involve the conservation of physical quantities. In a closed system, where no external forces are acting, both angular momentum and energy are conserved. This means that any changes in one quantity will result in corresponding changes in the other.

How is angular momentum used in real-world applications?

Angular momentum has many practical applications, such as in the design of vehicles and machines that rotate, such as helicopters and turbines. It is also important in fields such as astronomy, where it helps scientists understand the movement of celestial bodies.

Is angular momentum affected by external forces?

Yes, external forces can affect an object's angular momentum. For example, if an object is spinning and an external force is applied, the direction or speed of the rotation may change. However, if the external force is removed, the object will continue to rotate with its modified angular momentum.

Back
Top