Final answer:
Two forces that act on a body when it is immersed in water are gravity, which pulls the object downward, and buoyant force, which pushes it upward. An additional force, drag, opposes the object's movement through water.
Step-by-step explanation:
When a body is immersed in water, two primary forces act on it: gravity, which pulls the object downward, and buoyant force, which pushes the object upward. There is also a force known as drag that opposes the movement of the object through the water. Gravity is a field force that causes an object to have weight, and this weight is experienced by the body in the water. The buoyant force, on the other hand, is a result of the pressure exerted on all sides of the immersed body, which is higher at greater depths due to water pressure. This results in a net upward force on the object. The drag force experienced by the body is dependent on the velocity and shape of the body moving through the fluid and acts to resist the motion.
For example, while swimming, a person feels heavier pressure on the lower part of the body because it is at a greater depth than the upper part, resulting in the buoyant force. Additionally, as a swimmer moves through water, they experience drag force, which increases as they move faster or decreases when they streamline their body to present less surface area to the direction of motion.