A block $A$ exerts a force on $B$ of magnitude $20 \mathrm{N}$. Calculate the magnitude of force exerted by $B$ on $A$.

Draw F.B.D. of the sphere of mass $M$ placed between a vertical wall and ground as shown in the figure (all surfaces are smooth).

A block of mass $1 \mathrm{kg}$ placed on ground is pulled by a string by applying $10 \mathrm{N}$ force: $(g=10 \mathrm{m} {\mathrm{s}}^{-2})$

(i) Draw $\mathrm{F}.\mathrm{B}.\mathrm{D}.$ of block.

(ii) Give action–reaction pair involved in the above problem.

Draw free body diagrams for masses $m$ and $M$ shown in the figure. Identify all action–reaction pairs between two blocks. The pulley is frictionless and massless and all surfaces are smooth.

Draw the $\mathrm{FBD}$ for the following individual parts of the systems:

A block of mass $m$ is placed on ground and an additional force $F=mg$ is applied on the block as shown in the figure. Calculate contact force between ground and block.

Two blocks of masses ${\mathrm{m}}_1$ and ${\mathrm{m}}_2$ are placed on the ground as shown in the figure. Two forces of magnitude $\mathrm{F}$ act on ${\mathrm{m}}_1$ and ${\mathrm{m}}_2$ in opposite directions.

(i) Draw $\mathrm{F}.\mathrm{B}.\mathrm{D}.$ of masses ${\mathrm{m}}_1$ and ${\mathrm{m}}_2$.

(ii) Calculate the contact force between ${\mathrm{m}}_1$ and ${\mathrm{m}}_2$.

(iii) What will be the value of normal force between ${\mathrm{m}}_1$ and ${\mathrm{m}}_2$.

(iv) Calculate force exerted by ground surface on mass ${\mathrm{m}}_1$ and ${\mathrm{m}}_2$

A sphere of mass $m$, radius $R$ placed between two vertical walls having separation $d$ which is slightly greater than $2R$:

(i) Calculate force exerted by walls on the sphere.

(ii) Calculate force exerted by ground surface on the sphere.