Question

Find out acceleration of the block. Initially the block is at rest.

${\mu }_s$ = 0.5

${\mu }_k$ = 0.3

• A. 0.1 m/$s^2$
• B. 2.1 m/$s^2$
• C. 1 m/$s^2$
• D. 2 m/$s^2$

Answer 1

The correct option is B

2.1 m/$s^2$

0$\le$ $f_s$ $\le$ ${\mu }_s$ N

0 $\le$ $f_s$ $\le$ 50

51 > 50

Now

$\therefore$ Block will move but if the block starts moving then kinetic friction is involved.

$f_k$ = ${\mu }_k$N = 0.3 $\times$ 100 = 30 N

$\therefore$ 51 - 30 = 10a

$\therefore$ a = 2.1 m/ $s^2$