Answer
given,
length of bar = 80 cm
mass of the bar = 10 kg
smaller mass = 4 kg
distance = 20 cm


taking moment about B






difference between two scale = 8 - 6
= 2 N
In this case to find the weight of an object you must use the formula.
W = mg
The railroad tracks will move with the plate boundaries
A gravity and or D angular momentum
Yes, Hawaiian Coral reef fish live in the sunlight zone or in other words the euphotic zone.