A free body diagram is a simple diagram that represents all the forces acting on an object. It shows the object as a dot or a box and the forces as arrows pointing in the direction of the force with labels to indicate the type of force and its magnitude. This helps to analyze the motion of the object based on the net force acting on it.
Gravity.
Newton's first law describes something special that results from the sum of all the external forces (including gravity) on an object. The forces exerted by the object on other things or on itself are irrelevant to that result, and so the free body diagram used to calculate that result gives the correct result even though we completely neglect forces exerted by the body. Why is Newton's first law important? That's a different question (see below).
The two opposing forces acting on an object as it floats in a fluid are buoyancy (upward force exerted by the fluid on the object) and gravity (downward force exerted by the object's weight). At equilibrium, these forces balance each other, causing the object to float.
When an object is at rest, the forces acting upon it are balanced - there are no unbalanced forces.
The forces that act on a stationary object are typically the gravitational force pulling the object down and the normal force exerted by the surface supporting the object.
Action-Reaction Forces.
The force exerted on a scale by an object and other forces acting.
un-accelerated
Gravity.
Newton's first law describes something special that results from the sum of all the external forces (including gravity) on an object. The forces exerted by the object on other things or on itself are irrelevant to that result, and so the free body diagram used to calculate that result gives the correct result even though we completely neglect forces exerted by the body. Why is Newton's first law important? That's a different question (see below).
The two opposing forces acting on an object as it floats in a fluid are buoyancy (upward force exerted by the fluid on the object) and gravity (downward force exerted by the object's weight). At equilibrium, these forces balance each other, causing the object to float.
When an object is at rest, the forces acting upon it are balanced - there are no unbalanced forces.
Inertia.
However many there are exerted on the object. Usually there is gravity, friction, and another force exerted on the object.
The "reaction" force.
Buoyant forces
The forces that act on a stationary object are typically the gravitational force pulling the object down and the normal force exerted by the surface supporting the object.