Question

A 60 kg body is pushed with just enough force to start it moving across a floor and the same force continues to act afterwards. The coefficient of static friction and sliding friction are 0.5 and 0.4 respectively. The acceleration of the body is –

• A. 6 m/s²
• B. 4.9 m/s²
• C. 3.92 m/s²
• D. 1 m/s²

Answer 1

Answer: (D)

1 m/s²

Answer 2

Force required to start the motion,

F = m_smg

Once body starts sliding friction becomes kinetic.

\ a = $\frac { \mathrm { F } - \mu _ { \mathrm { k } } \mathrm { mg } } { \mathrm { m } } = \frac { \mu _ { \mathrm { s } } \mathrm { mg } - \mu _ { \mathrm { k } } \mathrm { mg } } { \mathrm { m } }$ = (m_s – m_k)g = 1m/s²