Materials - Potential Energy

Question 1

Potential Energy

Answer 1

• Potential Energy means stored energy
• The potential energy of a system is the energy stored in a system due to its configuration (for example, its position or orientation).

Question 2

Types of potential energy

Answer 2

• There are many types of potential energy, these can be:
‣ Gravitational Potential energy, which is
given by the equation E = mgh
‣ Elastic Potential Energy, which is given by
the equation E = 1/2kx^2
‣ Electric Potential Energy in a uniform
electric field, which is given by the equation
j = -qEx
‣ Magnetic Potential Energy which is given by
the equation E=−μB
‣ Gravitation potential energy due to two
point masses, which is given by the
equation E=-((GMm)/r)
‣ Electric Potential Energy due to a point
charge, which is given by an equation

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Question 3

Negative Potential Energy

Answer 3

Potential energy may also be negative because of where you set your zero point, the point where your potential energy is zero. This may lead to a negative potential energy, as if you set the zero point as something which already exceeds your potential energy, or something happens which decreases the potential energy in the object below the zero point, you would end up with a negative potential eergy.

Question 4

Potential Energy of a Spring

Answer 4

• Potential energy is not simply a measure of the work an object may do concerning gravity
• it is more generally a measure of the work an object can do as a function of its position or configuration (meaning that different parts of the spring have moved by different amounts).
• For example, to compress a spring, work must be done against the force that is trying to maintain the spring in its natural state. If the force trying to maintain it is not dissipated through heat, or left in the motion of the spring, then it will become potential energy. which obeys Hooke’s Law.

Question 5

Potential Energy and Work

Answer 5

• For an object to increase in potential energy, external work must be done against the force acting on the object, which means the work done by the force considered will be negative.
• The potential energy is the amount of energy stored that can be extracted afterwards, therefore it must be the negative of the external work done to get it there.

Question 6

Gravitational and Electric Potential Energy

Answer 6

• GPE and EPE are energies stored as a result of a mass or charge’s position in the gravitational or electric field.
• As the forces are both inverse square forces described by vector fields, their potential energies behave very similarly
• The potential energy is the work done to move a charge or mass from the surface at which zero potential energy is defined, to the point where one wants to know the potential
• If the force is attractive then this is equal to the kinetic energy that the object would gain falling from this point to the surface.

Question 7

Conservative Forces

Answer 7

• if the work done by a force acting on an object moving between two points in space is independent of the path taken between them, then we say that the force is conservative.