1. **Problem statement:** A body weighing 10 N is placed on a rough inclined plane at an angle $\theta$. The body is about to move under the action of its weight only. Another body of the same material weighing 20 N is placed on the same plane. We need to determine the state of the second body. 2. Since the first body is about to move, the frictional force is at its maximum value, balancing the component of weight parallel to the plane. 3. The frictional force $f$ is proportional to the normal force $N$, which depends on the weight and the angle $\theta$. 4. For the first body (weight $W_1=10$ N), the frictional force $f_1$ balances the component of weight down the plane: $$f_1 = W_1 \sin \theta$$ 5. The maximum friction force is $$f_1 = \mu N_1 = \mu W_1 \cos \theta$$ where $\mu$ is the coefficient of friction. 6. Equating the two expressions for friction at the point of impending motion: $$\mu W_1 \cos \theta = W_1 \sin \theta \implies \mu = \tan \theta$$ 7. For the second body (weight $W_2=20$ N), the frictional force is $$f_2 = \mu W_2 \cos \theta = W_2 \sin \theta$$ since $\mu = \tan \theta$. 8. The component of weight down the plane for the second body is $$W_2 \sin \theta$$. 9. Since frictional force scales with weight, the second body will also be at the point of impending motion. 10. The direction of impending motion depends on the direction of the force causing motion. Since the first body is about to move down, the second body will also be about to move down. **Final answer:** (a) be about to move down.