A block of mass M=1.0 kg is dragged over a horizontal surface by a force F=20.0N. The block is displaced a distance d=10.0 m, the friction force Ff is 5.0 N. What is the work done by the weight Fg?

To find the work done by the weight (force of gravity, Fg), we need to understand the concept of work and learn how to calculate it.

Work is defined as the product of force and displacement. Mathematically, it can be expressed as:

Work (W) = Force (F) * Displacement (d) * Cos(θ)

Where:
- Work (W) is measured in joules (J).
- Force (F) is the force applied to the object, measured in newtons (N).
- Displacement (d) is the distance the object is moved, measured in meters (m).
- θ (theta) is the angle between the force and the direction of displacement.

In this case, we are interested in finding the work done by the weight (Fg). Weight can be represented as the product of mass and acceleration due to gravity. Mathematically, it can be written as:

Weight (Fg) = mass (M) * acceleration due to gravity (g)

To calculate the work done by the weight (Fg), we need to find the force exerted by the weight and multiply it by the displacement.

Given:
- Mass (M) = 1.0 kg
- Force (F) = 20.0 N (applied force)
- Displacement (d) = 10.0 m
- Friction force (Ff) = 5.0 N

To proceed, we need to calculate the force exerted by the weight (Fg). The acceleration due to gravity is approximately 9.8 m/s^2.

Weight (Fg) = mass * acceleration due to gravity
Fg = M * g
Fg = 1.0 kg * 9.8 m/s^2

Therefore, the force exerted by the weight (Fg) is Fg = 9.8 N.

Now, we can calculate the work done by the weight.

Work (W) = Force (Fg) * Displacement (d) * Cos(θ)

Since the weight acts vertically downward, and the displacement is horizontally, the angle between them is 90 degrees. The cosine of 90 degrees is 0.

Work (W) = Fg * d * Cos(θ)
W = 9.8 N * 10.0 m * Cos(90 degrees)
W = 9.8 N * 10.0 m * 0
W = 0 J

Therefore, the work done by the weight (Fg) is zero joules (0 J) since the angle between the weight and the displacement is 90 degrees.