I think the answer is just Option C, cause Alpha radiation has an atomic mass unit (amu) of 4, since alpha radiation is just a helium nucleus.
Gravity is pulling you down and friction is slowing you down so you don't plummet to the ground at super high speeds.
Answer:
Explanation:
Given

Volume Flow rate 
Length 
radius 

According to Hagen-Poiseuille Equation
difference in Pressure is given






Copper because it contains alot of electricity
Answer
By F = -kx {-ve just indicating the sign of the force}
=>35 = k x (85-50) x 10^-2
=>k = 100 N/m
Again by F = -kx