Mass Object Affect Falling Speed Liquid Environmental Sciences Essay

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The purpose of this experiment was to determine how a mass of an object would affect its speed when sinking through glycerin or water. I became interested in this idea when watching a movie on submarines which are designed to be able to travel through water at high speeds.

I knew before I started my investigation that glycerin is heavier than water, thus glycerin will slow down the speed of a falling object. I also knew that the heaviest object falls faster than the light objects due to my knowledge and observation of a falling stone which is obviously faster than a falling bird feather.

Why the investigation is important?

The problem was important to investigate because when I was watching a movie about submarine, I wondered about submarine as being a heavy object and how it travels through water so smoothly with very high speed. I was trying to see if object's mass affects the speed it travels through water.

The speed of falling weights through water and glycerin is tested in this research. I think that the heaviest weight will be the first to fall. The materials used in my experiment are cylinder, 3 different weights, stopwatch, water and glycerin. The results turned out to be that the heaviest weight reached the bottom of the cylinder first, while the second was the middle weight and the lightest weight was the last. Thus my hypothesis turned out to be correct as the heaviest weight fell in the shortest time. I have also observed that it is really difficult to maintain the same amount of force on each weight, as a workaround the same dropper dropped the 3 weights from the same distance. For further research enhancement, I suggest that weight should have been hanged on U shape wood board freely and use scissors to release the weights to ensure that no external force was added to the weight. Also tested weights need to be of the same shape and size to eliminate any additional variables. I have really gained lots of information about gravity, weights and fluid friction.

Background Information

Aristotle theorized that heavy objects accelerate faster than lighter ones.

Galileo observed the dropping of varies masses from the Leaning Tower of Pisa. He noticed that the acceleration is independent of their mass which leads him to a conclusion that a falling or rolling objects appeared to accelerate at the same rate independently of their mass.

Aristotle's theory was based on the philosophy of logic in that it seemed obvious that heavier objects would fall faster than light objects, while Galileo's theory was based on actual observation and experimentation.

Galileo "Italian physicist, mathematician and philosopher " Aristotle "Greek philosopher (384 BC - 322 BC) "

(15 February 1564 - 8 January 1642)

Summarizing Aristotle's View and Galileo's experiment

Aristotle held that there are two kinds of motion for objects, natural and unnatural. Unnatural (or "violent") motion is when something is being pushed, and in this case the speed of motion is proportional to the force of the push. Natural motion is when something is seeking its natural place in the universe, such as a stone fall.

For the natural motion of heavy objects falling to earth, Aristotle stated that the speed of fall was directly proportional to the weight, and indirectly proportional to the density of the medium the body was falling through.

Galileo has done multiple experiments to answer the question that heavy objects fall at practically the same rate.

Observation won't only answer this question --- as all objects fall too fast. To make any kind of measurement of the speed, the motion must somehow be slowed down.

That's why I have selected Glycerin instead of water to slow down the speed of a falling object!!!!!

Mass and Weight

The mass of an object is measure of the amount of matter in the object. While the weight of an object is defined as the force of gravity on the object and may be considered as the mass times the acceleration of gravity, w= mg. While the real weight of a human is determined by his mass and the acceleration of gravity.

Falling objects holds a force that's much high than its weight.


While the real weight of a human is determined by his mass and the acceleration of gravity, one's real or effective weight comes from the fact that he is supported by other objects like floor, chair and table. If all the supported objects are removed all of a sudden the person will begin to fall freely and he feels weightless - Thus weightlessness refers to a state of being in free fall.

The state of weightlessness can be reached in quite a lot of ways, all of which involve significant physical principles as seen in below figures.

What is Friction?

A friction is the wicked force of all motions. Regardless if you throw an object to the right the friction switches the direction of the falling object so we call it the opposite wicked force.

Friction is actually a force that appears whenever two things are rubbed against each other. Although two objects might look smooth, microscopically, they're very rough and jagged, as seen in below picture:

As objects slide against each other, a crush and drag force against each other is produced. This is where friction comes from. Friction is useful as it has a lot to do with our daily life. Without it, we wouldn't be able to walk, sit in a chair, climb stairs, or use a mouse to surf the web. Everything would just keep slipping and falling all over the place.

"Fluid" friction

Fluid friction is what happens with liquids and gases (In Physics, liquids and gases are both called "fluids")

Fluid friction depends on how thick the fluid is (its "viscosity"), object's shape and object's speed.

Aircraft and car designers want to reduce drag, so that they can go fast without having to waste too much fuel.

To reduce friction, we need a shape that the fluid can flow past easily and smoothly. This tends to mean using long, pointed, "streamlined" shapes.

Speed, Acceleration and Forces

Speed is how fast an object's position changes with time at any given moment. A car traveling 70 KM per hour is traveling faster than a car with a speed of 40 KM per hour. Average Speed is the total distance traveled by the amount of time.

The description of both speed and direction of a moving object is its velocity. Two objects can have the same speed but different velocities if they are moving in different directions.

When a moving object's velocity increases with time, the object is accelerating. The acceleration of an object falling freely near Earth's surface due to gravity is called a G.

A force is a push or pull exerted by one object on another. Forces change the motion of objects.

Friction is a force that opposes the motion of an object sliding over another. Friction acts any time the surfaces of objects are in contact.

When an object moves through a gas, such as air, or any liquid, there is forces that resist motion. This force is called drag force. As an object moves through the air, the air molecules hit into it (a drag force) and cause the object to slow down. Drag force depends on speed. The faster the speed, the greater the drag force.

Gravity is a force of attraction that exists between all objects with mass. The force of gravity between two objects depends on the masses of the two objects and the distance between the objects. The closer the objects are to each other, the stronger the force of gravity exerted on each other. The force of gravity between Earth and any other object is called the weight of the object.

Sources of Error:

The sources of error in this project were mainly human error; the dropper can not exactly maintain the same external force on dropping the weight, the stopwatch holder could waste some seconds before stopping the watch. I have encountered and taken care of another error by changing the research topic slightly as I wanted to test the speed of falling balls with different weights (ping pong, Squash and Golf) in glycerin, but the ping pong and the squash ball float in the glycerin. That is why I used 3 different weights instead of the 3 balls.

Applications of investigations:

I think that engineers creating submarines or any under water traveling objects will greatly benefit from my research.

Further Research:

Next time I will try to be more accurate in my experiment by using different weights with same size and shape and try to get rid of human error as much as possible.