8)
a)
Explain by an example what is meant by potential energy. Write
down the expression for gravitational potenial energy of a body
of mass m placed at a height h above the surface of the earth.
9) a)
What do you understand by the term “transformation of
energy" ? Explain with an example.
b)Explain the transformation of energy in the following cases :
i) A ball thrown upwards.
ii) A stone dropped from the roof of a building.
10) a)
State and explain the law of conservation of energy with an
example.
b)Explain how, the total energy a swinging pendulum at any
instant of time remains conserved. Illustrate your answer with
the help of a labelled diagram.
(the one who answers correctly will be marked as brainliest)
Answers
Answer:
Explanation:
Climbing stairs and lifting objects is work in both the scientific and everyday sense—it is work done against the gravitational force. When there is work, there is a transformation of energy. The work done against the gravitational force goes into an important form of stored energy that we will explore in this section.
(a) The weight attached to the cuckoo clock is raised by a height h shown by a displacement vector d pointing upward. The weight is attached to a winding chain labelled with a force F vector pointing downward. Vector d is also shown in the same direction as force F. E in is equal to W and W is equal to mg h. (b) The weight attached to the cuckoo clock moves downward. E out is equal to mg h.
Let us calculate the work done in lifting an object of mass m through a height h, such as in Figure 1. If the object is lifted straight up at constant speed, then the force needed to lift it is equal to its weight mg. The work done on the mass is then W = Fd = mg h. We define this to be the gravitational potential energy (PEg) put into (or gained by) the object-Earth system. This energy is associated with the state of separation between two objects that attract each other by the gravitational force. For convenience, we refer to this as the PEg gained by the object, recognizing that this is energy stored in the gravitational field of Earth. Why do we use the word “system”? Potential energy is a property of a system rather than of a single object—due to its physical position. An object’s gravitational potential is due to its position relative to the surroundings within the Earth-object system. The force applied to the object is an external force, from outside the system. When it does positive work it increases the gravitational potential energy of the system. Because gravitational potential energy depends on relative position, we need a reference level at which to set the potential energy equal to 0. We usually choose this point to be Earth’s surface, but this point is arbitrary; what is important is the difference in gravitational potential energy, because this difference is what relates to the work done. The difference in gravitational potential energy of an object (in the Earth-object system) between two rungs of a ladder will be the same for the first two rungs as for the last two rungs.
An energy transformation is the change of energy from one form to another.
Example- most of the time chemical energy is released in the form of heat energy and this transformation from chemical energy to heat, or thermal energy is called exothermic reactions.
However, as the ball moves upward, it slows down as its initial kinetic energy is transformed into potential energy. ... When a ball is thrown straight up into the air, all its initial kinetic energy is converted into gravitational potential energy when it reaches its maximum height.
FOR THE B 2 QNS REFER THE LINK IN THE CHAT I WILL POST
Law of Conservation of Energy Examples
The law of conservation of energy is a law of science that states that energy cannot be created or destroyed, but only changed from one form into another or transferred from one object to another. This law is taught in physical science and physics classes in middle schools and high schools, and is used in those classes as well as in chemistry classes.
Everyday Examples: Law of Conservation of Energy
The law of conservation of energy can be seen in these everyday examples of energy transference:
Two football players collided on the field, and both went flying backwards. Energy was transferred from each player to the other, sending them in the opposite direction from which they had been running.
Claire threw the ball and it hit her mother's vase, knocking it over. Energy was transferred from the moving ball to the stationary vase, causing the vase to move.
Fingers hitting piano keys transfer energy from the player's hand to the keys.
Billy hit the punching bag, transferring energy from his arm to the stationary bag.
The dog ran in into the Christmas tree and knocked it over. Energy was transferred from the moving dog to the stationary tree, causing the tree to move.
When the car hit the road sign, the sign fell over. Energy was transferred from the moving car to the stationary sign, causing the sign to move. No energy was lost in the transfer.
Potential energy of oil or gas is changed into energy to heat a building.
When a bowling ball knocks over pins that had been standing still, energy is transferred from the ball to the pins. No energy is lost.
Beth hit the wall so hard that she put a hole in it. Energy was transferred from Beth's body to the drywall, causing it to move.
the simple pendulum works by the thread and ball the ball weight both side and pressure works
Answer:
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