Explain gravitatiional potential energy and how do we measure it with an example
Answers
Answer:
Gravitational energy is the potential energy held by an object because of its high position compared to a lower position. ... For example, a pen being held above a table has a higher gravitational potential than a pen sitting on the table. Gravitational potential energy is mechanical energy minus kinetic energy.
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Answer:
We all know instinctively that a heavy weight raised above someone's head represents a potentially dangerous situation. The weight may be well secured, so it is not necessarily dangerous. Our concern is that whatever is providing the force to secure the weight against gravity might fail. To use correct physics terminology, we are concerned about the gravitational potential energy of the weight.
All conservative forces have potential energy associated with them. The force of gravity is no exception. Gravitational potential energy is usually given the symbol U_gU
g
U, start subscript, g, end subscript. It represents the potential an object has to do work as a result of being located at a particular position in a gravitational field.
Consider an object of mass mmm being lifted through a height hhh against the force of gravity as shown below. The object is lifted vertically by a pulley and rope, so the force due to lifting the box and the force due to gravity, F_gF
g
F, start subscript, g, end subscript, are parallel. If ggg is the magnitude of the gravitational acceleration, we can find the work done by the force on the weight by multiplying the magnitude of the force of gravity, F_gF
g
F, start subscript, g, end subscript, times the vertical distance, hhh, it has moved through. This assumes the gravitational acceleration is constant over the height hhh.
\begin{aligned}U_g &= F_g\cdot h \\ &= m\cdot g \cdot h\end{aligned}
U
g
=F
g
⋅h
=m⋅g⋅h
A weight lifted vertically to acquire gravitational potential energy.
A weight lifted vertically to acquire gravitational potential energy.
A weight lifted vertically to acquire gravitational potential energy.
If the force were to be removed, the object would fall back down to the ground and the gravitational potential energy would be transferred to kinetic energy of the falling object. Our article on conservation of energy includes some example problems that are solved through an understanding of how gravitational potential energy is converted to other forms.
What is interesting about gravitational potential energy is that the zero is chosen arbitrarily. In other words, we are free to choose any vertical level as the location where h=0h=0h, equals, 0. For simple mechanics problems, a convenient zero point would be at the floor of the laboratory or at the surface of a table. In principle however, we could choose any reference point—sometimes called a datum. The gravitational potential energy could even be negative if the object were to pass below the zero point. This doesn't present a problem, though; we just have to be sure that the same zero point is used consistently in the calculation.