Ultraviolet radiation from the sun is controlled by the ozone but if it infiltrates into the atmosphere it becomes a hazard. The uv reaches our eyes and darkens the retina and blurs vision. The fovea becomes insensitive and the cells dormant. This causes gradual blindness.
Answer:
5m/s²
Explanation:
Given parameters:
Mass of wagon = 10kg
Force of pull = 70N
Frictional force = 20N
Unknown:
Acceleration of the wagon = ?
Solution:
Frictional force is a force that opposes motion.
The net force is given as:
Net force = mass x acceleration
Force of pull - Frictional force = mass x acceleration
Insert the parameters and solve;
70 - 20 = 10 x acceleration
50 = 10 x acceleration
Acceleration = 5m/s²
Answer:
The kinetic energy is 86.6 zepto joules.
Explanation:
Given that,
Number of orbit n =5
We know that,
Bohr's radius for hydrogen atom is

Now, put the value of n in the formula of radius


We need to calculate the kinetic energy
Using formula of kinetic energy

Put the value into the formula


We know that,

The kinetic energy is


Hence, The kinetic energy is 86.6 zepto joules.
CHECK COMPLETE QUESTION BELOW
you stood on a planet having a mass four times that of earth mass and a radius two times of earth radius , you would weigh?
A) four times more than you do on Earth.
B) two times less than you do on Earth.
C) the same as you do on Earth
D) two times more than you do on Earth
Answer:
OPTION C is correct
The same as you do on Earth
Explanation :
According to law of gravitation :
F=GMm/R^2......(a)
F= mg.....(b)
M= mass of earth
m = mass of the person
R = radius of the earth
From law of motion
Put equation b into equation a
mg=GMm/R^2
g=GMm/R^2
g=GM/R^2
We know from question a planet having a mass four times that of earth mass and a radius two times of earth radius if we substitute we have
m= 4M
r=(2R)^2=4R^2
g= G4M/4R^2
Then, 4in the denominator will cancel out the numerator we have
g= GM/R^2
Therefore, g remain the same
<span>If you faced the situation when popcorn is heated over a flame and the kernel burst opened the thing which caused that is definitely : the air and water vapor which remain in the kernell have expanded.
Hope that helps.
</span>