B.) <span>The amp is the unit for "Current"
Hope this helps!</span>
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

They all produce light and stuff
True: Friction depends on the types of surfaces involved and how hard the surfaces push together.