Introduction of Upthrust

Upthrust

Upthrust is the generated lift force exerted by the liquid or gas and when an object is partially immersed or completely sink into the liquid. Upthrust occur when an object is immersed in liquid, whether it is partially or completely sink. Which causes the weight loss to the object.

We can see teh effect of  upthrust in our daily life by taking this example of an instance:

"Try lifting weight in a swimming pool and and then try lifting the weight outside the pool. Which one weighs more?"

The answer is in the swimming pool, this is because the upthrust force of the water will act as an"helping hand" that will make us easier to lift the weight.

Archimedes Principle stated that the upward buoyant force (force exerted by a fluid that opposes the weight of an immersed object) that is exerted on a body when immersed in a fluid, whether fully or partially submerged, is equal to the weight of the displaced water.

Upthrust = apparent loss of weight of object = weight in air - weight in liquid

The way ship float really describe how upthrust works.

 

The reason that a ship floats is that it displaces a lot of water. The water pressure is balanced in every direction except upward, means there is net force that pushes the ship upwards. The force which pushes the ship up is called the buoyancy force. Even though ship has a big mass, but the volume are also very big. that is why the density will be relatively small. But if we take a look on a piece of gold ring. Eventhough the mass is relatively small, but the volume itself is also very small also. that is why gold ring which has denser density will sink in water. While ship that has less dense density because of its big volume, which will cause the ratio of density to volume to be very low will float on water.

Density

Density

The density of a material is defined as the mass per unit volume.It’s a measure of how tightly the atoms of a material are packed unlike what many would think, density has nothing to do with the hardness of the material or size.  

For example a 1 cm long play-doh surface can be soft and squishy compared to 100 cm long styrofoam. However the density of a 1 cm long play-doh is bigger compare to a 100 cm long styrofoam. We can prove that when we try to float play-doh and styrofoam in water. Styrofoam will float, however play-doh will sunk. This is because the density of play-doh compare to water is bigger eventough it has small volume and no hardness at all. But styrofoam has lower density than water, that is why it will float. The symbol most often used for density is ρ (the lowercase Greek letter rho). Different materials usually have different densities. Solid have the biggest density, because their atom are packed very closely and tight to one another. Then we have liquid, their atom are pack quite closely to one another but the attraction between the atom is not as strong as solid. The last we have air, which have the least density. This is because their atom are far away from one another.

    

where ρ is the density, m is the mass, and V is the volume.

       The units are                      =  kilograms/meter3  =  kg/m3

Examples:

Material	Density (kg/m3)
air	1.29
ice	917
water	1000
aluminum	2700
lead	11300
gold	19300

Introduction of Vector & Scalar Quantities

Vector & Scalar Quantities

Scalars are quantities that are fully described by a magnitude only.  For example:

• Time - Scalar quantities often refer to time; the measurement of years, months, weeks, days, hours, minutes, seconds, and even milliseconds.

• Speed and temperature - Two more commonly used scalar quantities in physical calculations are speed and temperature. As long as they did not show any directional movement they will be considered as a scalar quantities. For instance, the measurement of speed in miles or kilometers-per-hour or the measurement of the temperature of the medium both remain scalar quantities as long as they aren’t associated with the direction of the medium’s travel.  

While vectors, are quantities that are fully describe by both magnitude and direction. William Rowan Hamilton (an Irish physicist, astronomer, and mathematician, who made important contributions to classical mechanics, optics, and algebra) has been credited many times for inventing vectors. Vectors must have the same units in order for them to be added or subtracted. For example:

• Force has a value and a direction. You push or pull something with some strength (magnitude) in a particular direction (left or right, north, south, east, or west, or even up or down.)

• weight has a value and a direction. Your weight is proportional to your mass (magnitude) and is always in the direction towards the centre of the earth.

Exercise on differentiating Vector and Scalar Quantities:

1) The football player was running 10 miles an hour towards the end zone.

This is a vector because it represents a magnitude (10 mph) and a direction (towards the end zone). This vector represents the velocity of the football player.

2) The volume of that box at the west side of the building is 14 cubic feet.

This is a scalar. It might be a bit tricky as it gives the location of the box at the west side of the building, but this has nothing to do with the direction of the volume which has a magnitude of 14 cubic feet.

3) The temperature of the room was 15 degrees Celsius.

This is a scalar, there is no direction.

4) The car accelerated north at a rate of 4 meters per second squared.

This is a vector as it has both direction and magnitude. We also know that acceleration is a vector quantity.

Introduction to Newton's Law of Motion

Newton's Law of Motion

Sir Isaac Newton Law of Motion change the way scientist understand physic. Sir Isaac Newton can be named as the greatest scientists and mathematicians that ever lived. He was born in England on December 25, 1643. He went on to Trinity College Cambridge. While at college he became interested in math, physics, and astronomy. While Newton was in college he was deeply affected by Galileo Galilei Inertia theory, so he tries to come up with his own law of motion theory. Later on in his life,Newton's ideas were so good that Queen Anne knighted him in 1705. His accomplishments laid the foundations for modern science and revolutionized the world. Sir Isaac Newton died in 1727.

Newton's first Law of Motion:

An object at rest will remain at rest unless acted upon an external force. An object in motion will  continues to stay in motion with the same speed and in the same direction until acted upon an external  force. This law is also known as “inertia”

From the gif above we can see that the skater move in constant speed and direction until it hit a rock. this is because the wheel of the skate have the tedency to remain at its current motion and speed. However, when the skate hit the rock; the wheel of the skate is acted upon a force that was created by the force when they hit and make the wheel to stop. However, we can also see the blue test tube falling when the skate stop in an instant. this is becase the blue test tube has the tedency to keep moving forward. but since the skate stop the test tube fall down.

Newton's seccond Law of Motion:

The relationship between an object's mass m, its acceleration a, and the applied force F is F = ma. Acceleration is produced when a force acts on a mass. The greater the mass (of the object being accelerated) the greater the amount of force needed (to accelerate the object). Actually it is a general knowledge that the heavier the object, it require more force to be move.

From the illustration above, we can see that it require a lot more force to kick a brick wall and try to make it fall. That is because the wall has a very high inertia to stay in its current state compare to the ball. When the blue test tube kick the ball, the ball easily move that is because it is exerted to an externall force. It is possible to break the wall and make it fall, as long the kick can be exert a force that is strong enough to break the inertia of the wall.

Newton's third  Law of Motion:

Newton's third Law of Motion state that "For every action there is an equal and opposite re-action" which means that for every force there is a reaction force that is equal in size, but opposite in direction. That is to say that whenever an object pushes another object it gets pushed back in the opposite direction equally hard.

From the illustration above, we can see that the blue test tube that kick the wall feel pain. this is because when it kick the wall with force, the wall also exert equall amount of force but just in the opposite direction. So actually the wall also feel the pain, but because it is a non-living object it cannot show its emotion.

Key Term & It's Proper Usage

Key Term

• Distance: is how much an object has travel, and some might interpret distance as the space between two objects to one another

• Displacement: is how much an object has travel compare to its initial position

• Speed: is the rate at which an object can move or currently moving

• Velocity: is the speed of something in a given direction

• Acceleration: is the increase of rate in a moving object

• Deceleration: is the decrease of rate in a moving object

Example in Real Life:

Thomas runs 500 m every day at 5 O’clock in the afternoon from his house to a market.  And directly come back home before even entering the market.  He runs 5 m/s always, until he can see the market from his eyes. Then Thomas accelerate 3 m/s^2. When he is on his way back home he decelerates until 6 m/s.

Answer:

Distance: 1000 m

Displacement: 0 m

Velocity: at first: 5 m/s

      On the way back: 6 m/s

Acceleration: 3 m/s^2

Deceleration: 2 m/s^2

Case Study

Case:

The “Madly” Genius Galileo Galilei and His Effect to the Development of Newton’s Law

Case Presentation:

Sixteenth century, an era where physicist around the view that the study of physic are deeply rooted to the Aristotelian study to the point where a few European thinkers would have considered the possibility that it couldn’t be challenged. Where Professors all over Europe taught highly of Aristotle's study and perspective to their students.

However, just like the phrase “ one in a million” emerge a young man who not only questioned, but ultimately overturned the Aristotelian study and theory, his name is Galileo Galilei (1564-1642.). Galileo Galilei, was an Italian astronomer, physicist, engineer, philosopher, and mathematician who played a major role in the scientific revolution during the Renaissance.

At first Galileo Galilei mind was set to the study of astronomy, but when his model of cosmos that was developed from the idea of an astronomer Nicolaus Copernicus (1473-1543.) who made a case, based purely on astronomical observation, that the Sun and not Earth was at the center of the universe  was later forced to be “banned” by the Pope in Rome because it is presumed as going against Aristotle point of view; Galileo Galilei turn to Physic.

Galileo Galilei chose to challenge Aristotle on an issue that to most people at the time seemed relatively settled: the claim that objects fall at differing speeds according to their weight (an idea that was proposed by Aristotle). In order to proceed with his aim, Galileo Galilei had to introduce a number of innovations, and indeed, he established the basic principle kinematics, or the study on how objects move.

Aristotle had indicated that when objects fall, they fall at the same rate from the moment they begin to fall until they reach their "natural" position. Galileo Galilei, on the other hand, suggested an aspect of motion, unknown at that time yet , but now became an important part physics: known as acceleration.

In discussing the movement of the object and his study , Galileo Galilei and his student  had developed the term inertia along the way, to describe inertia as the tendency of an object in motion to remain in motion, and an object at rest to remain at rest.

Which as we all know will be the  starting point of Newton's three laws of motion, and Newton would be greatly affected on the concept of inertia that was developed first by Galileo Galilei. Sir Isaac Newton (1643-1727) was an English physicist and mathematician who is widely recognised as one of the most influential scientists of all time and a key figure in the scientific revolution. he was renowned for his three Law of Motion:

1. First law of motion: An object at rest will remain at rest, and an object in motion will remain in motion, at a constant velocity unless or until outside forces act upon it.
2. Second law of motion: The net force acting upon an object is a product of its mass multiplied by its acceleration.
3. Third law of motion: When one object exerts a force on another, the second object exerts on the first a force equal in magnitude but opposite in direction.

Real life application of Newton’s Law:

Impact of a Moving Football

let say you are watching and supporting your friend in one of his sunday morning football match. Suddenly out of player accidentally kick the ball in your direction and the ball fly away and keep flying in your direction (Newton's first Law of Inertia), as an act of reflex to stop the ball you wave your hand and let your hand got hit by the ball, and so the ball bounce after touching your hand. When this happen it cause pain to your hand. This is caused by  the force (F=m.a)(Newton's second Law) that was exerted by the ball when it touch your skin. However, the ball also experience this “pain” just it cannot show it. simply because it is a nonliving thing. But the ball bounce back because it experience an equal and opposite force acting on it when it touch your hand (Newton third Law).