Wouldn't it be neat if an electron falling closer to the nucleus ... emitting a
photon ... actually gave out more energy than it needed to climb to its original
energy level by absorbing a photon ! If there were some miraculous substance
that could do that, we'd have it made.
All we'd need is a pile of it in our basement, with a bright light bulb over the pile,
connected to a tiny hand-crank generator.
Whenever we wanted some energy, like for cooking or heating the house, we'd
switch the light bulb on, point it towards the pile, and give the little generator a
little shove. It wouldn't take much to git 'er going.
The atoms in the pile would absorb some photons, raising their electrons to higher
energy levels. Then the electrons would fall back down to lower energy levels,
releasing more energy than they needed to climb up. We could take that energy,
use some of it to keep the light bulb shining on the pile, and use the extra to heat
the house or run the dishwasher.
The energy an electron absorbs when it climbs to a higher energy level (forming
the atom's absorption spectrum) is precisely identical to the energy it emits when
it falls back to its original level (creating the atom's emission spectrum).
Energy that wasn't either there in the atom to begin with or else pumped
into it from somewhere can't be created there.
You get what you pay for, or, as my grandfather used to say, "For nothing
you get nothing."
A is right because I took the test
Every atom has electrons. When you add new electrons to the wire, they will be passed on to an atom. The electrons keep passing from atom to atom until it reaches the light source, basically. It's kinda like that one song "100 jugs of milk" or whatever it's called. Each atom passes the atom next to it an electron.
Well simple the warm water then replaces the cold current that sinks to the ocean floor.
Answer:
(a)
(b) It won't hit
(c) 110 m
Explanation:
(a) the car velocity is the initial velocity (at rest so 0) plus product of acceleration and time t1
(b) The velocity of the car before the driver begins braking is
The driver brakes hard and come to rest for t2 = 5s. This means the deceleration of the driver during braking process is
We can use the following equation of motion to calculate how far the car has travel since braking to stop
Also the distance from start to where the driver starts braking is
So the total distance from rest to stop is 352 + 88 = 440 m < 550 m so the car won't hit the limb
(c) The distance from the limb to where the car stops is 550 - 440 = 110 m