Answer:
(1) A hot drink cooling to room temperature.
(2) The combustion of natural gas.
Explanation:
The spontaneous process is the process in which there is a release of energy and moves towards lower energy and a more thermodynamically stable energy state. All the natural processes are spontaneous.
There are two processes which are spontaneous in the given question are:
(1) A hot drink cooling to room temperature: In this, there is a decrease in energy and also it is a natural process and we know that all the natural processes are spontaneous.
(2) The combustion of natural gas: The fire is an example of an exothermic reaction. The combustion is a combination of a decrease in energy and an increase in entropy. So, this process occurs spontaneously.
Answer:
Voltage across the capacitor is 30 V and rate of energy across the capacitor is 0.06 W
Explanation:
As we know that the current in the circuit at given instant of time is
i = 2.0 mA
R = 10 k ohm
now we know by ohm's law
so voltage across the capacitor + voltage across resistor = V
Now we know that
here rate of change in energy of the capacitor is given as
Answer:
the spear will end up above the fish relative to the actual position of the fish.
Explanation:
due to refraction of light coming from the fish the fish will appear slightly above from its real position
So due to this refraction the spearfisher will throw the spear directly at the image of the fish due to which it will not reach the position of fish but it will reach the position above the fish.
So here we can say that the spear will end up above the fish relative to the actual position of the fish
Answer:
I would say that I agree with the one that said that each hill must be lower than the previous one and use the principle of conservation of energy to explain.
Explanation:
Roller coaster are usually designed such that its total energy remains conserved at any point on the track. Now, the law of conservation of energy states that the total energy of an isolated system remains constant; it is said to be conserved over time. At certain height on the track, the total energy of the roller coaster is in form of potential energy, which gets converted to kinetic energy as soon as it starts sliding down the hill till get to the hill's endpoint where it has maximum kinetic energy. The cycle of sliding from a high point on the track to a low point on the track means there is potential energy is converted to kinetic energy and kinetic energy then converts back to potential energy and the cycle continues.
However, due to the effect of gravity and frictional force between the track and the coaster, the energy of the coaster is gradually reduces, so it becomes a bit difficult for the coaster to move to the next hill of the same height. It is for this reason that each hill must be lower than the previous one, so that the coaster can overcome the next hill's height with its reduced energy until it loses all its energy and comes to a stop.
