What is the Conservation of Energy Principle Used for in AP Physics Homework?

In summary, the problem involves calculating the speed of a clay and a pan using kinematics. The clay starts at rest and accelerates at a rate of 9.8 m/s^2 due to gravity, over a distance of H. The equation vf^2=vi^2+2a(d) is used to solve for the final velocity of the clay, which is equal to the square root of 19.6H. For the pan, it is assumed that its speed is the same as the clay's, but this assumption may need further clarification.
  • #1
meganw
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Homework Statement



http://img515.imageshack.us/img515/6163/physicscopydi7.gif [Broken]

This is AP Physics C 2003 M2 by the way...

Homework Equations



Kinematics: vf^2=vi^2+2a(d)

The Attempt at a Solution



a) Speed of the clay uses kinematics. Clay starts at rest, accelrates at gravity=9.8, and the distance is H:

vf^2=vi^2+2a(d)

vf^2=2(9.8)(H)

vf=[tex]\sqrt{}19.6H[/tex]

b) The speed of the pan...hmmmm..so I would guess that it's the same as the speed of the clay just was, but I'm not sure if I can make that assumption.

Thanks for the help, by the way. =)
 
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  • #2
p.s. I'm going to sleep right now and I won't have time to discuss this problem tomorrow, but if someone is willing to just post all the steps to the solution of this AP problem, you could be my savior. Thank You!
 
  • #3


I would first like to commend your use of the kinematics equation to solve for the speed of the clay. Your solution for part (a) is correct, as the final velocity of the clay will indeed be the same as the speed at which it is launched from the spring.

For part (b), you are correct in questioning whether or not the speed of the pan will be the same as the speed of the clay. In this scenario, we can use the conservation of energy principle to determine the speed of the pan. Since the system (clay + pan) starts with a certain amount of potential energy (due to the compression of the spring), that energy must be conserved and converted into kinetic energy as the clay is launched.

Therefore, the kinetic energy of the system (clay + pan) will be equal to the potential energy stored in the spring, which can be calculated as 1/2kx^2, where k is the spring constant and x is the distance the spring is compressed. Since we know the spring constant (k = 1000 N/m) and the distance the spring is compressed (x = 0.2 m), we can calculate the total energy of the system.

Next, we can use the kinetic energy equation, 1/2mv^2, to solve for the velocity of the pan. We know the mass of the pan (m = 0.5 kg) and we can calculate the total kinetic energy of the system from the previous step. Setting these two equations equal to each other and solving for the velocity of the pan will give us the correct answer.

In summary, for part (b), we cannot assume that the speed of the pan will be the same as the speed of the clay, but we can use the conservation of energy principle to determine the correct velocity of the pan. I hope this helps!
 

1. What is the definition of spring constant in AP Physics?

The spring constant, denoted by k, is a measure of the stiffness of a spring. It is defined as the force required to stretch or compress a spring by a certain distance.

2. How is spring constant calculated?

Spring constant can be calculated by dividing the force applied to the spring by the displacement caused by the force. This value is often referred to as the spring's stiffness.

3. What is the unit of measurement for spring constant in AP Physics?

The unit of measurement for spring constant is Newtons per meter (N/m) in the SI system, or pounds per inch (lb/in) in the imperial system.

4. How does spring constant affect the behavior of a spring?

A higher spring constant means that the spring is stiffer and requires more force to stretch or compress it. On the other hand, a lower spring constant indicates a less stiff spring that is easier to stretch or compress.

5. Can the spring constant of a spring change?

Yes, the spring constant of a spring can change depending on factors such as the material of the spring, its length, and temperature. In general, a spring with a higher stiffness will have a higher spring constant.

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