Question

An elevator accelerates upwards, with $a=1.0m/s^2$. Inside the elevator are two stacked blocks, each $2.0kg$ in mass.
How much normal force does the bottom book exert on the top book?

• A. $17.62N$
• B. $19.62N$
• C. $21.62N$
• D. $35.24N$
• E. $39.24N$

Answer 1

The correct option is C $21.62N$

Since both the blocks also move upwards with acceleration $a=1m/2^2$,

the free body diagram of the block is

$ma=N-mg$
$⟹N=m(g+a)$

$=2\times (9.81+1)$ newton

$=21.62N$