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Specific heat of air at constant pressure = 1.005KJ/kg-K Apparently the hot air leaves the house while equal quantity of the cool air passes inside (Neglecting the small specific volume changes between the hot and the cold air) So the situation can be sampled as a scenario where there is continuous draw down of the thermal energy from the air.
Initially there were 10 bulbs of 60 Watt power
So total power of all bulbs = 60 * 10 = 600 W
now each bulb used for 4 hours daily
so total energy consumed daily
now we have total power consumed in 1 year
cost of electricity = 10 cents/ kWh
so total cost of energy for one year
Now if all 60 Watt bulbs are replaced by 30 Watt bulbs
So total power of all bulbs = 30 * 10 = 300 W
now each bulb used for 4 hours daily
so total energy consumed daily
now we have total power consumed in 1 year
cost of electricity = 10 cents/ kWh
so total cost of energy for one year
total money saved in 1 year
Answer:
Explanation:.
Given that
First car velocity is 2m/s
Second car velocity is 9m/s.
At a certain time the first car is 8m from intersection
And at the same time second car is 6m from intersection.
The rate of change of distance, i.e dx/dt, which is the speed of the car.
Using Pythagoras theorem, their distance apart is given as
Z²=X²+Y²
Z²=6²+8²
Z²=36+64
Z²=100
Z=√100
Z=10m
Let assume the direction,
Let assume the first car is moving in positive x direction, then
dx/dt=2m/s
And also second car will be moving in negative y direction
dy/dt=-9m/s
Now, to know dz/dt, let use the Pythagoras formulae above
x²+y²=z²
differentiate with respect to t
2dx/dt+2dy/dt=2dz/dt
Divide through by 2
dz/dt=dx/dt+dy/dt
dz/dt=2-9
dz/dt=-7m/s
The rate of change of distance between the two body is -7m/s
Option B is correct
Answer:
An electron in the third shell has more energy than an electron in the second shell and An electron in the first shell has more energy than an electron in the second shell.
Explanation:
- Calcium has 20 electrons.
- Calcium does not "borrow" electrons. Calcium "donates" 2 electrons.
- Calcium ion (Ca2+) has 18 electron
- Calcium has 2 valence electrons.
- The element Ca, so calcium, has 20 electrons (so it also has 20 protons) this means that it has 2 electrons in its outer orbit, its relative atomic mass is 40.
Oxygen, Carbon dioxide and other small uncharged molecules can move through the cell membrane through a method called osmosis
osmosis is when there is a semipermeable membrane and molecules pass through it, where there is less concentration of molecules.