Question

A body of weight 64 N is pushed with just enough force to start it moving across a horizontal floor and the same force continues to act afterwards. If the coefficients of static and dynamic friction are 0.6 and 0.4 respectively, the acceleration of the body will be (Acceleration due to gravity = g)

• A. $\frac { g } { 6.4 }$
• B. 0.64 g
• C. $\frac { g } { 32 }$
• D. 0.2 g

Answer 1

Answer: (D)

0.2 g

Answer 2

Weight of the body = 64N

so mass of the body

$m = 6.4 \mathrm {~kg}$ , $\mu _ { s } = 0.6$ , $\mu _ { k } = 0.4$

Net acceleration $= \frac { \text { Applied force } - \text { Kinetic friction } } { \text { Mass of the body } }$

$= \frac { \mu _ { s } m g - \mu _ { k } m g } { m } = \left( \mu _ { s } - \mu _ { k } \right) g = ( 0.6 - 0.4 ) g = 0.2 g$