1. Given data

   • Mass of roller: $m=70\,\text{kg}$
   • Applied force: $F=200\,\text{N}$
   • Angle with horizontal: $30^\circ$
   • Acceleration due to gravity: $g=10\,\text{m s}^{-2}$

2. Weight of the roller $W=mg=70\times 10=700\,\text{N}$ This acts vertically downward.

3. Resolve the applied force vertically Since the roller is being pushed at an angle of $30^\circ$ with the horizontal, the vertical component of the force is downward.

   Vertical component: $F_y=F\sin 30^\circ=200\times \frac{1}{2}=100\,\text{N}$

4. Normal reaction The ground must balance both the weight and the downward vertical component of the push.

   So, $N = mg + F_y$ $N = 700 + 100 = 800\,\text{N}$

5. Match with options $N=800\,\text{N}$ Hence, the correct option is A.

Comparison with stored answer:

• Derived answer: A
• Stored correct answer: A
• They agree.