Ten one-rupee coins are put on top of each other on a table, Each coin has a mass m. Which of the following statements in not ture?

Options

A. (a)The force on the `6^(th)` coin due to `7^(th)` coin is 4mg (downwards)
B. (b)The force on the `6^(th)` coin to `7^(th)` coin is 4mg (downwards)
C. (c)The reaction of the 6th coin on the `7^(th)` coin is 4mg (upward)
D. (d)The total force on the `10^(th)` coin is `9mg` (downwards)

Answer

D

Explanation

(a) is correct. `6^(th)` coin has four coins on its top which exert a force 4 mg on it.
(b) is correct. `7^(th)` coin has three coins, placed over it. Thus `7^(th)` coin exerts a force 4mg on `6^(th)` coin (downwards)
(c) is correct
As what is explained in (b), the reaction of `6^(th)` coin is 4 mg (upward)
(d) is wrong. `10^(th)` coin, which is the topmost coin, experiences a reaction force of mg (upwards) from all the coins below it.