Question

A body of mass 2 kg is being dragged with uniform velocity of 2 m/s on a rough horizontal plane. The coefficient of friction between the body and the surface is 0.20. The amount of heat generated in 5 sec is

$( J = 4.2$ joule / cal and $\left. g = 9.8 m / s ^ { 2 } \right)$

• A. 9.33 cal
• B. 10.21 cal
• C. 12.67 cal
• D. 13.34 cal

Answer 1

Answer: (A)

9.33 cal

Answer 2

Work done = Force × Displacement

$= \mu m g \times ( v \times t )$

$W = ( 0.2 ) \times 2 \times 9.8 \times 2 \times 5$ joule

Heat generated Q $= \frac { W } { J }$ $= \frac { 0.2 \times 2 \times 9.8 \times 2 \times 5 } { 4.2 }$

$= 9.33$ cal