Potential Energy - Work Done etc

In summary, the conversation is about solving two physics questions. The first question involves two children of different masses holding onto a rope and one letting go while the other moves upward and then falls back to the ground. The second question involves a particle at rest on a hemisphere and finding its speed as it moves on the surface. The solution may involve drawing a diagram and using equations with variables such as mass, forces, and angles.
  • #1
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Please help me to solve the following question... I am really stuck.

1. Two children of mass 40 kg and 50 kg are holding on to the ends of a rope which passes over a thick horizontal branch of a tree. The parts of the rope on either side of the branch are vertical and the heavier child is moving downwards. A model is to be used in which the children may be considered as particles, and in which the rope is light and inextensible and is moving freely in a smooth groove on the branch. when the heavier child is moving at 2 m s^-1, she let's go of the rope. Calculate the further upward distance moved by the other child before falling back to the ground.
The motion described began with both children stationary. Calcuylate the distance they traveled before one let go of the rope.

2. A particle is at rest at the apex A of a smooth fixed hemisphere whose base is horixontal. Thhe hemisphere has centre O and radius a. The particle is then displaced very slightly from rest and moves on the surface where angle AQP=θ the particle has speed v. Find an expression for v in terms of a, g and θ.

Many thanks in advance!
 
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  • #2
What are you stuck on?

You have a system with masses and forces acting on them. Have you drawn a diagram?
 

FAQ: Potential Energy - Work Done etc

What is potential energy?

Potential energy is the energy an object possesses due to its position or state. It is stored energy that has the potential to do work.

How is potential energy calculated?

The amount of potential energy an object has is calculated by multiplying the object's mass, acceleration due to gravity, and height above the ground. The formula for potential energy is PE = mgh, where m is mass, g is the acceleration due to gravity, and h is the height.

What is work done?

Work done is the transfer of energy from one object to another by applying a force over a distance. It is measured in joules (J) and can be calculated by multiplying the force applied by the distance traveled.

How is potential energy related to work done?

Potential energy and work done are closely related, as work done is necessary to change an object's potential energy. For example, when lifting an object, work is done against gravity to increase the object's potential energy. Similarly, when an object falls, the potential energy is converted into kinetic energy as work is done by the force of gravity.

What are some examples of potential energy?

Some common examples of potential energy include a stretched spring, a raised weight, a compressed rubber band, and a charged battery. Other examples include a bow and arrow, a roller coaster at the top of a hill, and a book placed on a shelf.

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