A block of mass 10 kg starts sliding on a surface with an initial velocity of $9.8 \mathrm {~ms} ^ { - 1 }$. The coefficient of friction between the surface and block is 0.5 . The distance covered by the block before coming to rest is :[use $\mathrm { g } = 9.8 \mathrm {~ms} ^ { - 2 }$ ]
(1) 9.8 m
(2) 4.9 m
(3) 12.5 m
(4) 19.6 m

Q4. A heavy box of mass 50 kg is moving on a horizontal surface. If co-efficient of kinetic friction between the box and horizontal surface is 0.3 then force of kinetic friction is :
(1) 1.47 N
(2) 147 N
(3) 14.7 N
(4) 1470 N