Energy, Power, Work related question

In summary, the problem involves a pitcher rotating a 0.25kg ball around a vertical circular path with a radius of 0.6m and exerting a 50N force parallel to the motion of the ball. The speed of the ball at the top of the circle is 20m/s. Using the formula KE = 1/2mv^2 and PE = mgh, the speed of the ball upon release at the bottom of the circle can be calculated by setting the energy at the top equal to the energy at the bottom. This results in the equation vf = sqrt(1/2mvi^2+mgh-mgh)/m. However, this equation does not take into account the work done by the
  • #1
alevis
17
0
This isn't the actual problem given in the assignment. I've twisted it a bit because I want to see were I specifically go wrong in my calculations.
1. A pitcher rotates a 0.25kg ball around a vertcal circular path of radius 0.6m before releasing it. The pitcher exerts a 50N force directed parallel to the motion of the ball around the complete circular path. The speed of the ball at the top of the circle is 20m/s. If the ball is released at the bottom of the circle, what is the speed upon release?



2. KE = 1/2mv^2
PE = mgh
Energy at top = Energy at bottom.
1/2mvi^2+mgh = 1/2mvf^2+mgh.


3.vf = sqrt (1/2mvi^2+mgh-mgh)/m
 
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  • #2
Welcome to PF!

Hi alevis! Welcome to PF! :smile:
alevis said:
A pitcher rotates a 0.25kg ball around a vertcal circular path of radius 0.6m before releasing it. The pitcher exerts a 50N force directed parallel to the motion of the ball around the complete circular path. The speed of the ball at the top of the circle is 20m/s. If the ball is released at the bottom of the circle, what is the speed upon release?
…
3.vf = sqrt (1/2mvi^2+mgh-mgh)/m

What about the work done by the pitcher? :wink:

(and you're missing a 2)
 
  • #3
thanks alot
 

1. What is the difference between energy, power, and work?

Energy is the ability to do work or cause change. Power is the rate at which energy is transferred or work is done. Work is the application of a force over a distance. In simpler terms, energy is the capacity to do something, power is how quickly it can be done, and work is the actual activity.

2. How is energy measured and what are the units of measurement?

Energy is measured in joules (J) in the SI system. Other common units of measurement include kilowatt-hours (kWh) for large amounts of energy, and calories (cal) for smaller amounts.

3. What are the different forms of energy?

There are many forms of energy including mechanical, thermal, chemical, electrical, nuclear, and electromagnetic. Mechanical energy is associated with motion and position, thermal energy is associated with heat, chemical energy is associated with chemical reactions, electrical energy is associated with the movement of charged particles, nuclear energy is associated with the nucleus of an atom, and electromagnetic energy is associated with light and other forms of radiation.

4. What is the law of conservation of energy?

The law of conservation of energy states that energy cannot be created or destroyed, only transferred or converted from one form to another. This means that the total amount of energy in a closed system will remain constant over time.

5. How is power related to energy and work?

Power is the rate at which energy is transferred or work is done. This means that power is directly proportional to both energy and work. The more energy that is transferred or work that is done in a given amount of time, the higher the power will be. Mathematically, power = energy/work.

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