Describing Motion | Grade 7 Science DepEd MELC Quarter 3 Module 1

[Music] hi there in this video we will be describing motion in terms of distance or displacement speed or velocity and acceleration so let's get started many of the things around us move some move slowly like turtles and clouds while others move much more quickly like rockets and satellites because motion is so common it seems to be very simple but in science describing motion actually entails careful use of some definitions so what is motion motion is the act or process of moving or a particular action or movement of an object brought about by force motion is exhibited by a change in position the term speed velocity and acceleration are used to describe motion the motion of an object traveling in a straight path is called rectilinear motion thought of an object traveling a curved path is called curvilinear motion and that of an object traveling at certain angles is called angular motion how else can motion be defined what quantities are used to specifically describe the distance covered and the speed of a moving object taking any of the paths mentioned you will find answers as we go through this video when describing the motion of an object you must first be able to tell exactly where it is positioned describing exact position entails two ideas first describing how far the object is from the reference point and second describing its direction relative to that reference point a reference point is a place or object used for comparison to determine if something is in motion an object is in motion if it changes position relative to a reference point thus the initial position serves as the reference point objects that are fixed relative to earth such as a building a tree or a sign make good reference points distance is the measure of the interval between two locations measured along the actual path connecting them while the shortest path in a straight line between the initial position and final position is known as displacement take a look at this illustration the distance between the dog and the house as well as the distance between the cyclists in the house is 5 meters the displacement of the dog while moving in a straight line from its original position towards the house is five meters east while the displacement of the cyclists while moving in a straight line from her original position towards the house is 5 meters west even though they both move through equal distances their displacements are different because the dog moves to the east while the cyclist moves to the west let's try the sample problem on his way to school mike traveled 100 meters north 300 meters east 100 meters north 100 meters east and 100 meters north find the total distance traveled and determine the displacement made by mike to solve for total distance we simply add all the given distances we have 100 meters plus 300 meters plus 100 meters plus 100 meters plus 100 meters for a total distance of 700 meters to solve for total displacement let us look at the illustration you may have noticed that a figure forms a right triangle the displacement made is the hypotenuse while the given values make the leg on the y-axis and the leg on the x-axis the pythagorean theorem tells us that the relationship in every right triangle is a squared plus b squared is equal to c squared or c is equal to the square root of a squared plus b squared thus we get the formula displacement is equal to the square root of d sub x squared plus d sub y squared using the formula we can now solve for displacement total displacement equals the square root of d sub x squared plus d sub y squared first we add the distances 100 meters plus 300 meters and 100 meters plus 100 meters plus 100 meters we now have 400 meters squared and 300 meters squared then we add the squares of both numbers lastly we get 250 000 meters squared then get the square root of 250 000 meters squared which is 500 meters so mike has traveled a total distance of 700 meters and displaced a total of 500 meters on his way to school people usually associate the term speed with fast moving objects such as high speed cars and racing mics speed is the rate at which distance is covered at a given time speed is calculated by the distance traveled divided by the time elapsed we can express speed in terms of miles per hour kilometers per hour or meters per second [Music] when direction is associated with speed you will have a new quantity known as velocity thus velocity is a speed in a given direction velocity of an object changes when the speed changes the direction changes or both the speed and direction change a car driving along a highway from one town to another might have constant speed but the velocity changes nevertheless if you are moving along at 25 meters per second and then you come to a bend in the road your velocity changes because your direction changes velocity is calculated by the displacement divided by the time note that there are arrows on the symbols to indicate that velocity and displacement are vector quantities let's try calculating for speed rachel watches a thunderstorm from her window she sees a flash of lightning and begins counting the seconds until she hears the clap of thunder five seconds later assume that the speed of sound in air is 340 meters per second and the light was seen instantaneously how far away was the lightning bolt so we have the given values of 340 meters per second and 5 seconds to get the distance we can derive the formula from the formula for speed which is speed equals distance over time we can then get the formula for distance which is speed multiplied to time the given speed is 340 meters per second multiplied by the given time which is 5 seconds we can cancel out common units so the lightning bolt was 1 700 meters away from rachel's location let's have another example a car at rest starts moving and attains a speed of 50 meters per second in 15 seconds how far has the car traveled in 15 seconds our given values are the initial speed of zero final speed of 50 meters per second and time of 15 seconds we are asked to find the distance remember that we can derive the formula for distance from the formula for speed so distance equals speed multiplied by time since both the initial and final speed was provided we need to add these figures and divide them by 2 to get the speed of the object before we can multiply it with the time we now have 0 plus 50 meters per second divided by 2 which is equal to 25 meters per second we then multiply this to 15 seconds we can cancel out common units and we now have the distance traveled by the car which is 375 meters acceleration is usually associated with a change in speed when something speeds up we say it exhilarates but acceleration involves more than a change in speed it is a change in velocity defined as acceleration is equal to change in velocity over time the unit for acceleration is meter per second squared let's try calculating for exhilaration michael is driving his car at 30 meters per second when he sees a dog on the road ahead he slams on the brakes and comes to a stop in three seconds what was the exhilaration of michael's car so we have the given values of initial velocity of 30 meters per second final velocity of zero meters per second and time of three seconds the formula for acceleration is velocity over time since we have both the final velocity and initial velocity we need to subtract the final velocity to the initial velocity first before we can divide it with the time so 0 minus 30 meters per second divided by 3 seconds equals to negative 10 meters per second squared this means that the car slows down at the rate of 10 meters per second every second this negative acceleration is known as deceleration [Music] alright so here's a quick recap motion is the movement of an object brought about by force the reference point is used for comparison to determine if something is in motion distance is the interval between two locations measured along the actual path connecting them displacement is the shortest path in a straight line between the initial position and final position speed refers to how fast an object moves velocity refers to how fast and in what direction an object moves exhilaration is a change in velocity that's all for now we will be discussing about how to create and interpret visual representations of the motion of objects in our next video so stay tuned see you on our next video and don't forget to keep your minds busy if you like this video please subscribe to our channel and hit the notification icon for more videos like this

Channel: The Learning Bees

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Keywords: The Learning Bees, Department of Education, DepEd, MELC-Based, Most Essential Learning Competencies, Science, MELC, Grade 7, Motion, Distance, Displacement, Speed, Velocity, Acceleration, how to solve for, problem-solving, calculating, motion, types of motion, whats the difference between distance and displacement, whats the difference between speed and velocity, how to calculate for, physics, formula

Id: anbmdtutuAk

Length: 12min 35sec (755 seconds)

Published: Thu Mar 11 2021