A force acting on an object is said to be a static force if it does not change the size, position, or direction of that particular object. The force applied to a structure acts as a load to that particular structure, which is why static force is also known as a static load. The static force is independent of time because it does not involve any change in magnitude and direction with respect to time. Static force does not allow any sort of change and helps to maintain the state of equilibrium of the object. In a nutshell, the static force enables the forces acting on the body or the load to remain constant and allows the state of the body to remain unaffected.
Examples of Static Force
1. Weight of a Body
The weight of a body is nothing but the amount of gravitational force acting on it. The gravitational constant is the same for all the objects present on the surface of the earth; therefore, the weight of a body does not vary or change with change in location. Hence, the weight of a body is a prominent example of a static force.
2. Car Resting on a Bridge
A car resting on a bridge exerts a considerable amount of force and pressure on the contact surface between the bridge and the car. This force does not cause any change in the state, position, or shape of the car or the bridge. Hence, the type of force existing between the bridge and the car is known as static force.
3. Pushing a Heavy Block
While pushing a heavy block that does not move upon applying a significant amount of force, the presence of a force of friction can be felt. It has a magnitude greater than the applied force and acts on the block from the direction opposite to that of the applied force. This force does not allow any change in the position of the block. Therefore, it is called a static force.
4. A Portrait Hung on the Wall
When an object is hung on a wall, it is acted upon by a number of forces. The gravitational pull of the earth tends to pull the painting in a downward direction. At the same time, the push force and the reaction force offered by the wall keeps the painting in place. These forces do not make the painting change its position or state with respect to time. Hence, it serves to be an ideal example of static force.
5. Ship Floating on Water Surface
A ship floating on the surface of water experiences the effect of gravitational force and gets pulled towards the core of the earth, but the buoyant force presented by the water surface to the structure of the boat tends to push it in an upward direction. Both the forces acting from the opposite direction establish a balanced force. The balanced force acts as a static force that helps to maintain the stationary state of the boat and helps it to float on the surface.
6. An Object Placed on a High Surface
An object placed on a high surface possesses a significant amount of potential energy. The state of the body does not change, and the state of equilibrium is maintained. Therefore, the forces acting on such an object only contributes to preserve the state of the rest of the object. Thus, they are known as static forces.
7. A Person Standing on the Ground
When a person is standing on a rigid surface or on the ground, the force of gravitation and the reaction force offered by the ground in response to gravity both serve as static forces. The static force helps to maintain the state of rest. This static force can be easily converted into a dynamic force by inducing motion into the body by walking.
8. Pushing a Wall
When a person applies a push force to the surface of a well-built wall, it does not move. Even on increasing the intensity of the force, the wall remains rigid and stationary. This suggests the possibility of the presence of a force, which acts on the structure of the wall from the opposite direction and forbids any change in state or position of the wall. This force is known as a reaction force and in this case, it acts as a static force.
9. A Coolie Carrying Bags over Head
While a person is holding a bag on his head, his/her work done is said to be zero. However, he tends to lose energy and feel tired after a little time. This is because a force is required by the person to hold the bags or the suitcases in a stationary position. This force is static in nature.
10. A hook and loop Arrangement
A hook suspended in a loop does not fall or gets displaced from its position. This is because a force acting in between two objects forbids any type of change in the position or the location. The force acting on the arrangement, therefore, is balanced and static in nature.
