Forces are balanced when net force on the object is zero or the sum of all force on the object is zero.
For book kept on a shelf, the weight of the book in down direction is balanced by the normal force on the book by the shelf. hence the book kept on a shelf is an example of balanced force.
In case of air rushing out of balloon , the balloon experience a net force by the air coming out of it.
rolling over and falling off the bed , the object falls under gravity force.
a car speeding up accelerates. since it accelerates , it has net force on it.
Answer and Explanation:
Polar molecules are formed as a result of unequal sharing of electrons by the atoms in the molecule which creates polarization like that in water molecule.
If the electrons are shared equally by the atoms in the molecule then there won't be any polarization of the molecule and the molecule is non polar.
Electro-negativity is that property of an atom which lets it attract negative charges, i.e., electrons. The more the electro-negativity of an atom in the molecule the more are the chances of its polarization.
Vocabulary should be, I think:
I. Hypothesis
II. Evidence, data
III. Experiment
What is your question exactly?
Answer:
a) 0.022%
b) 10014.32 lb
Explanation:
a) Percentage uncertainty would be

Percent uncertainty is 0.022%
b) For 1 kg uncertainty mass in kg would be

Mass in pounds would be

Mass in pound-mass is 10014.32 lb