A block of metal of mass $2 \mathrm{kg}$ on a horizontal table is attached to a mass of $0.45 \mathrm{kg}$ by a light string passing over a frictionless pulley at the edge of the table.The block is subjected to a horizontal force by allowing the $0.45 \mathrm{kg}$ mass to fall. The coefficient of sliding friction between the block and table is $0.2$. Calculate the tension (in Newton) in the string. ($g=10 \mathrm{m}/{\mathrm{s}}^2$)

A block of metal of mass $2 \mathrm{kg}$ on a horizontal table is attached to a mass of $0.45 \mathrm{kg}$ by a light string passing over a frictionless pulley at the edge of the table.The block is subjected to a horizontal force by allowing the $0.45 \mathrm{kg}$ mass to fall. The coefficient of sliding friction between the block and table is $0.2$. Calculate the distance (in metres) the block would continue to move if, after $2$ seconds of motion, the string should break. ($g=10 \mathrm{m}/{\mathrm{s}}^2$)

On a smooth horizontal surface a block A of mass $10 \mathrm{kg}$ is kept. On this block a second block B of mass $5 \mathrm{kg}$ is kept. The coefficient of friction between the two blocks is $0.4$. A horizontal force of $30 \mathrm{N}$ is applied on the lower block as shown. The force of friction between the blocks is 

($g=10 \mathrm{m}/{\mathrm{s}}^2$)

A pebble of mass $0.05 \mathrm{kg}$ is thrown vertically upwards. Give the direction and magnitude of the net force on the pebble, during its upward motion. (Ignore air resistance and take $g=10 \mathrm{m} {\mathrm{s}}^{-2}$)