Question

The velocity-time graph of the figure shows the motion of a wooden block of mass $1kg$ which is given an initial push at $t=0$ along a horizontal table. Then:

• A. the coefficient of friction between the block and the table is $0.1$
• B. the coefficient of friction between the block and the table is $0.2$
• C. if the table was half of its present roughness, the time taken by the block to complete the journey is $4s$
• D. if the table was half of its present roughness, the time taken by the block to complete the journey is $8s$

Answer 1

The correct option is A the coefficient of friction between the block and the table is $0.1$

Using the equation of motion,

$v=u+at$

$⟹0=4+a\left(4\right)$

$⟹a=-1m/s^2$

Thus, retarding force$=Friction=ma=1=\mu mg$

$⟹\mu =0.1$