A boy weight 78n sits on a bag of cement weighting 50kg.find the reaction of the ground on the bag of cement and the boy.take g=10ms

The mass of the cement bag is $50 \, \text{kg}$ and the acceleration due to gravity $g = 10 \, \text{m/s}^2$.
The weight of the cement bag is given by $W_{\text{cement}} = m_{\text{cement}} \times g$.

The total downward force is the sum of the boy's weight and the cement bag's weight.
Boy's weight $W_{\text{boy}} = 78 \, \text{N}$.
Total downward force $F_{\text{total}} = W_{\text{boy}} + W_{\text{cement}}$.

According to Newton's third law, the reaction force from the ground is equal in magnitude and opposite in direction to the total downward force exerted on it.
Therefore, the reaction of the ground on the bag of cement and the boy is $578 \, \text{N}$.