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Introduction to Displacement · Acedra
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Introduction to Displacement
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physics is the most beautiful and important Discovery humans have ever made over Millennia people have used their brains to understand how the universe works at some point we realized the universe has certain laws which we couldn't change truly the beauty is that we are not finding anything new to the universe rather we are just decoding the universe's laws imagine you in City a and City B is located 100 km north of you you want to travel to City B by car but the main
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road is closed so you're forced to take another road of course that road is not straight so you travel that Crooked Road and finally reach your destination you calculate that the distance you traveled was 150 km what if you took the shortest possible distance this in physics is called displacement displacement does not take into consideration your path or how you traveled it is about where you start and where you end so let's say you started from zero and now you are 100 km
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North from City a the displacement is 100 km North traveling means you are moving at some level of speed but what is speed mathematically speed is equal to distance divided by Time Imagine you took the shortest path and reached your 100 km destination in 1 hour therefore the speed of your car is 100 kmph now we add velocity into the mix velocity takes into account the direction of movement as well as speed and displacement in our case as City B is North that means you're traveling 100
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km per hour northward so 100 km hour to the north is termed as our velocity thus speed is the rate of time at which an object moves along a path while velocity is the rate and direction of an object's movement now imagine you're going somewhere at a speed of 50 kmph and after 50 km you realize you forgot to pick up your friend so you return to your friend's home your friend's house is located 5 km north of your home the total distance traveled is 100 km but
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the displacement is 5 km North so over a total time period of 2 hours your speed was 50 kmph but your velocity was 2.5 kmph North therefore the velocity represents displacement over time but do you think you can travel all around the trip at the the same speed let's take another example you are at Point a and traveling towards point B which is located 120 m to the east you reach that point in 5 seconds then you move towards Point C which is located 60 M further Westward
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from point B which you reach in 1 second there are two time intervals here thus we can calculate the average speed 120 + 60 = 180 M 180 m / 5 + 1 = 6 seconds so the average speed is 30 m/s but what about average velocity the displacement here is 60 m east and the time interval is 5 + 1 that's equal to 6 seconds so the average velocity is 10 m/s Eastward once again you're traveling in a car when suddenly a policeman stops you what will you do there are two options one you can apply the brakes and
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stop the car or the other way you can accelerate and speed away so what is acceleration acceleration is the rate of change of an object's velocity with respect to time let's walk through this imagine you have two vehicles a truck and a car your truck takes 30 seconds to reach 60 kilm per hour from zero and your car takes just 10 seconds to reach 60 km per hour from zero from this we can see how much the speed increases every second acceleration is final velocity minus initial velocity divided
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by time rate the car's final velocity is 60 kmph the initial velocity is 0 km/ hour and the time taken is 10 seconds so acceleration is 6 km/ hour per second it means that the acceleration increases by 6 km/ hour every second to more easily understand we change the hours into seconds imagine the car is already in motion with an initial velocity of 10 m/s and a of acceleration of 5 m/s squared so at 0 seconds the velocity is 10 m/s after 1 second the velocity will
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be 15 m/s after 2 seconds the velocity will be 20 m/s thus the acceleration tells us how fast the velocity is changing now let's delve into some real physics during acceleration we can feel a force pushing in the opposite direction if the car accelerates forward we get pushed back backward into the seat and if the car turns right we get pushed towards the left this basic example of classical physics is beautifully explained by the celebrated scientist Isaac Newton Newton was
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thinking like this if we throw a ball why does it slow down and fall to the ground after some time as we all know he identified this as Earth's gravity pulling the ball down gravity is an external force acting on the ball as well as friction and air resistance are external forces first we start with gravity in this universe everything has a certain Mass two massive objects attract each other according to their Mass The more mass the greater the attraction objects with greater mass
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attract lighter objects towards them therefore as the Earth has more mass than the ball the ball falls to the Earth's surface the standard unit of mass is kilogram but what is weight and how is it different from mass mass refers to the amount of matter present in an object it does not vary anywhere in the universe but weight isn't like that for example if a ball weighs 10 kg on Earth we will not get the same weight on the moon why is that as we already see massed objects have a certain
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gravitational force they pull other massed objects towards them how powerful they pull depends on their mass for example our Earth pulls other objects at 9.8 m/s squar this means objects accelerate at the value of 9 .8 m/s Square towards the Earth's surface due to Earth's gravity for comparison the moon's gravitational force is 1.62 m/ second Square so the weight equals the mass multiplied by the gravitational force if the object's mass is 80 kg we get their weight on Earth as 784 kg Ms
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squared or simply 784 newtons on the moon the same object's weight will be just 130 Newtons as we have multiply 80 by the moon's gravitational force 1.62 thus weight is not the same as mass it is a force thus mass is the measurement of the amount of matter contained in an object and weight is the measurement of how strong gravity pulls on the same object since weight is a force and gravitational pole is simply acceleration we can rephrase it like this Force equals mass time acceleration
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this is Newton's second law f is equal to ma this means that force can induce acceleration in an object acceleration depends on the amount of force applied and heavier objects require more Force for acceleration than lighter ones for example consider two boxes which have masses of 50 kg and 100 kg respectively if you apply 20n on both boxes the 50 kg box will have a higher acceleration than the 100 kg box this means acceleration is inversely proportional to the mass of
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the object if you want to accelerate a 5 kg box across a frictionless surface at an acceleration rate of 4 m/s Square how much force do you need to apply to that box just simply put the values into this equation you will get the answer 20n similarly if you apply a constant 20n force on a 5 kg box you can determine how much the Box can accelerate second by second here we use the term frictionless surface what is that we already see that friction is ALS Al an external Force
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when the surfaces of two objects contact each other a force is created that acts on each object this Force resists the motion of the object some surfaces have more or less frictional force than others for example the surface of glass has less frictional force than rough surfaces for example when we apply the brakes to a car the car's tires stop rotating and press firmly against the road creating increased friction which then causes the car to stop much quicker
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the same reason behind this is present when we drive during rainy days because water has low friction the road and the car's tires are unable to press so firmly together and so we feel the effects of slipperiness while driving then what if there is no external force acting on an object this is where Newton's first law of motion comes into play every object will remain at rest or in uniform motion in a straight line unless an external Force acts upon it uniform motion refers to constant
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velocity or no changes in the velocity for example imagine you're traveling in a car at constant velocity you won't feel any force on your body you feel your stationary but once you accelerate the car you can feel that some Force pushes you to the seat similarly when applying the brakes the friction Force resists your velocity when the car's movement suddenly stops you're pushed forward another example is the electric fan continuing to spin for a period after the electricity is turned
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turned off what brings the spinning to a stop are external forces such as air resistance and motor's friction these are examples on Earth but we know that the Voyager spacecraft is traveling through space without using fuel or engines this is also because of Newton's first law of motion in deep space there are no external forces such as friction gravitational pull or air resistance there is no Force bringing the Voyager probe to a halt so it remains in constant motion unless an asteroid or
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space Rock of some kind collides with voyager there is nothing that can change its velocity now imagine a ball placed on the ground it is at rest but how does it remain at rest because gravitational pull continues to be applied to the ball it pulls the ball towards the center of gravity that is the center of the earth simultaneously the ground applies an equal force in the opposite direction this is called the normal force these these two forces balance each other so
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the ball remains at rest now the object's net force is zero if we want to move the ball we need to increase the net force so now a boy kicks the ball and it gains some net force therefore the ball is in motion but eventually after a certain time interval it stops moving why because there are other forces such as friction and air resistance applying from the opposite direction the ball stops however when you kick a ball you can feel a noticeable sensation of feedback in your foot this is because
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you are exerting force on the ball and at the same time the ball is also returning some Force to you here comes Newton's third law every action has an equal and opposite reaction for example when you jump your legs apply a force to the ground and the ground applies the equal and opposite reaction force that propels you into the air the best example of the third law is rocket launching when a rocket launches the the rocket engine produces hot exhaust gases that flow downwards at extreme speed
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because of the opposite reaction the rocket gets pushed upwards this force is greater than the Rocket's mass and it's also greater than the Earth's gravitational pole so the rocket lifts upwards once a rocket successfully launches from the Launchpad the second law of motion applies f is equal to ma the rocket receives the same constant force from the fuel expulsion so it gets momentum and gains acceleration second by second and the rocket speed increases once it escapes the Earth's
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gravitational pole and enters space there is no external Force to stop the rocket so they turn off the engine as it already has momentum Newton's first law applies without fuel the spaceship continues to travel through
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space
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