Analysis:

To solve this problem, we need to find the coefficient of static friction between the surface and the body, given that the body is held against a rough vertical wall by applying a force normal to the wall.

Given:
- Mass of the body (m) = 5 kg
- Force normal to the wall (N) = ?
- Coefficient of static friction (µ) = 0.3

Solution:

To find the force normal to the wall, we need to consider the forces acting on the body in the vertical direction.

Forces acting on the body:
1. Weight (mg): The weight of the body acts vertically downwards and is given by the formula W = mg, where m is the mass of the body and g is the acceleration due to gravity (9.8 m/s²). Therefore, the weight of the body is W = 5 kg * 9.8 m/s² = 49 N.

2. Force normal to the wall (N): This force is acting perpendicular to the wall and balances the weight of the body. Since the body is just held against the wall, the magnitude of the force normal to the wall is equal to the weight of the body, N = 49 N.

3. Force of static friction (fs): The force of static friction acts parallel to the surface and opposes the motion of the body. Its magnitude is given by the formula fs = µN, where µ is the coefficient of static friction and N is the force normal to the surface.

Since the body is just held against the wall, the force of static friction must be equal to or greater than the force applied in the opposite direction. Therefore, fs ≥ F. In this case, the force applied in the opposite direction is the force normal to the wall, which is 49 N.

Using the formula for the force of static friction, fs = µN, we can substitute the given values to find the force of static friction:

fs = 0.3 * 49 N = 14.7 N.

Therefore, the force of static friction between the surface and the body is 14.7 N.

163.3 N