Dubnium is a synthetic element ... Number 105. It can be created
in a laboratory but it's not found in nature.
Fifteen (15) different isotopes of Dubnium have been created. They all
have 105 protons in the nucleus of every atom, but they have anywhere
from 256 to 270 neutrons in each nucleus.
The most stable isotope of Dubnium is ²⁶⁸Db , with 163 neutrons in the
nucleus. That form of Dubnium atom has a 50-50 chance of surviving
for around 28 hours before it falls apart.
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Answer:
μ =tanθ
Explanation:=
The ratio of the force of static friction and the normal reaction is equal to tanθ. F=mgsinθ. R = mgcosθ.
μ=tanθ
Answer: 
Explanation:
Given
Length of plank is 1.6 m
Force
is applied on the left side of plank
Force
is applied 43 cm from the left end O.
Mass of the plank is 
for equilibrium
Net torque must be zero. Taking torque about left side of the plank

Net vertical force must be zero on the plank
