A block of mass $$5 \mathrm{~kg}$$ is placed at rest on a table of rough surface. Now, if a force of $$30 \mathrm{~N}$$ is applied in the direction parallel to surface of the table, the block slides through a distance of $$50 \mathrm{~m}$$ in an interval of time $$10 \mathrm{~s}$$. Coefficient of kinetic friction is (given, $$g=10 \mathrm{~ms}^{-2}$$):

As shown in figure, a $$70 \mathrm{~kg}$$ garden roller is pushed with a force of $$\vec{F}=200 \mathrm{~N}$$ at an angle of $$30^{\circ}$$ with horizontal. The normal reaction on the roller is

(Given $$\mathrm{g=10~m~s^{-2}}$$)