What is the difference between air resistance and upthrust?

Answer 1

Air resistance is probably best explained when compared to parachuting.

There is quite a bit of physics involved in skydiving, but lets start with the basics. Once you leave the plane there are essentially only two forces acting on you: gravity pulling you down, and air friction. The friction with the air mostly adds up to push in the opposite direction from the direction you are moving, so basically it pushes up on you and your equipment.

Air resistance increases as your speed increases, so when you first start dropping and are moving slowly, gavity is stronger than the air resistance and you speed up, accelerating towards the ground. However the faster you drop, the stronger the air resistance is and so eventually you are moving so fast that the air resistance is equal in strength to gravity and you don't accelerate any more. You have reached terminal velocity for your current body position.

Why does body position come into it? Because air resistance also depends on the shape of the object (you) and so by tucking in your arms and legs you can reach a faster terminal velocity than if your arms and legs are spread out. But skydivers don't splay their arms and legs to slow down per se. They are trying to achieve a position of dynamic stability.

Dynamic stability is what allows an arrow to fly nose first. If the arrow starts to flip sideways, the air resistance against the fletching is greater than the resistance at the nose, and the arrow automatically goes back to its initial orientation. Likewise, skydivers don't want to be tumbling end over end and out of control, so they trail their arms and feet behind them to act like the feathers on the arrow.

Upthrust is easier explained with hot air ballooning. Upthrust is the force that is pushing an object up rather than down. The hot air displaces a balloon, producing upthrust. This upthrust is balanced by the weight of the balloon.

The balloon displaces a volume of air equal to its own volume. The air displaced is heavier than the air in the balloon as hot air is lighter than the cold air of same volume.

As the upthrust produced is the same as the weight of the air displaced, the force of the upthrust is greater than the weight of the balloon. Thus, the balloons keep rising till the upthrust is equal to the weight of the balloon acting downwards.

Answer 2

Oh, dude, air resistance is like when the air is all up in your face trying to slow you down, while upthrust is like when the water's trying to push you back up when you're trying to sink. So, it's like air vs. water, but they both just want to mess with your plans of moving smoothly through them.

Answer 3

Air resistance, also known as drag, is the force that opposes the motion of an object as it moves through the air. It depends on the shape and speed of the object. Upthrust, on the other hand, is the upward force exerted on an object immersed in a fluid, such as water or air, due to the pressure difference between the top and bottom of the object. Upthrust is also known as buoyancy force and is responsible for objects floating in fluids.

Answer 4

Air resistance is the force that opposes the motion of an object through the air, slowing it down. Upthrust, on the other hand, is the buoyant force that pushes an object upward when it is submerged in a fluid, like water. The key difference is that air resistance acts on objects moving through the air, while upthrust acts on objects submerged in a fluid.