Perimeter = 2 ( L + W )
32 = 2 ( L + W )
16 = L + W
L = 16 - W
Area = L W
63 = L W
63 = (16-W) W
63 = 16W - W²
-W² + 16 W - 63 = 0
By factorizing W = 9 or W = 7
So the dimensions are 7 and 9
Answer: The second force applied to the doorknob
Explanation:
The formulae for torque is simple the product of the applied force and the perpendicular distance.
The greater the perpendicular force, the greater the torque assuming a constant value of force.
Applying the force at the doorknob gives for a greater distance between the force and the turning point compared to applying the force at the midpoint of the door ( which is at a shorter distance)
Answer :
Velocity will be 
Explanation:
We have given glass surface has a diameter of 1.5 mm
And charge q = 1.60 nC
Radius of electrons orbit r = height of electron above surface + radius of sphere = 
Force on electron is given by
, here q is charge on sphere and e is charge on electron

This force work as centripetal force
So 

v = 
Answer:
Explanation:
When the positively charged half shell is brought in contact with the electroscope, its needle deflects due to charge present on the shell.
When the negatively charged half shell is brought in contact with the positively charged shell , the positive and negative charge present on each shell neutralises each other .So both the shells lose their charges .The positive half shell also loses all its charges
When we separate the half shells , there will be no deflection in the electroscope because both the shell have already lost their charges and they have become neutral bodies . So they will not be able to produce any deflection in the electroscope.
Answer:
Most of the oxygen in the atmosphere is in the form of O2, which means it is made up of molecules containing two oxygen atoms. Ozone, however is O3, which means it is made up of molecules containing three oxygen atoms. O2 is what we breath, and what plants release from photosynthesis. Ozone occurs naturally high in the stratosphere, where it absorbs ultraviolet light, protecting us here on the surface from skin cancer. Ozone can also occur closer to the surface of the earth as a pollutant. It is formed from reactions with O2 and chemicals emitted from factories and cars. It comes in the form of smog.
So in general:
Oxygen (O2): Essential to human life
Ozone (O3) in the stratosphere: essential to protecting life on earth
Ozone (O3) on the surface of the earth: toxic to human life, caused by pollution