In Bohr's atomic model, he proposed that the electrons are revolving around the nucleus in their respective orbitals. There are 5 kinds of orbitals: the s, p, d and f orbitals. They differ in their energy level, shape and number of subshells. Each subshell holds two oppositely spinning electrons. The s has 1 subshell, p has 3, d has 5 and f has 7. You arrange the orbitals into energy levels just like how you write them in an electronic configuration.
In the first energy level, you only have one 1s orbital. In the second energy level, you have one 2s and one 2p orbital, the 2p having more energy than 2s. The other levels are shown in the picture.
Answer:
B) A stack of books is carried at waist level across a room
Explanation:
Work is defined as:
where
F is the force applied
d is the displacement of the object
is the angle between the direction of the force and of the displacement
From the formula, we see that the work done is zero when the force and the displacement are perpendicular to each other. Let's now analyze each situation:
A) A bookcase is slid across carpeting. --> work is done, because the force that pushes the bookcase is in the same direction of the displacement
B) A stack of books is carried at waist level across a room. --> no work is done, because the force to carry the book is vertical, while the displacement of the books is horizontal
C) A chair is lifted vertically with respect to the floor. --> work is done, because the force that lifts the chair is vertical, and the displacement is vertical as well
D) A table is dropped onto the ground. --> work is done, because the force of gravity (that makes the table falling down) is vertical and the displacement of the table is also vertical.
The gravitational potential energy
gpe = mgh
Answer:
Explanation:
Given that,
The initial speed of a car, u = 0
Time, t = 18 s
Distance, d = 390 m
We need to find the acceleration of the car. Let it is a. Using the second equation of motion to find it.
or
So, the acceleration of the car is 
.
Answer:
600,000,000 degree C
Explanation:
This stage is the last stage and is refereed to as supernova. In the beginning of this stage, gravity pulls the inner core and crush it, due to which fusion of atoms starts. Carbon and Oxygen fuse together and the temperature is about of 600,000,000 degree C.
The most heavier atom that can be formed out of this fusion is the iron. The moment all the atoms becomes of iron, no further fusion is possible hence that body emits radiation of high intensity and collapse causing a big supernova.
