Konsep Vektor Fisika [LENGKAP] - Part 1 : Vektor Fisika Kelas 10

In this video we will discuss the material and examples of the 10th class physics vector

Previously, we have discussed the magnitude of the vector and the magnitude of the scalar in chapter 1. This time we will focus our discussion on the magnitude of the vector. First, we will first discuss the concept of a vector. A vector is a magnitude that has a value and direction. For example, the speed, acceleration, and the pattern of these three majorities have values ​​and directions. Then, the image and writing of the vector.

For example, we have a vector that leaves from position a and ends at b. For vector ab, this is the same as a, where a is the base of the vector, the key is the end of the vector, and the definite mark ab is the same as the definite a, which is the major vector. Next, about the equality of vectors.

Two vectors are said to be the same if they are large and have the same direction. As an illustration, pay attention to the following image. This is vector AB or vector A. This is the same as vector PQ or vector P. Well, these two vectors have the same length and the direction is the same to the right. So we say these two vectors are the same. Then about the vector mathematical operation. The vector mathematical operation that we will discuss here is the number and division of vectors.

later in the next video we will also discuss the multiplication of points and the vector curve for the method of multiplication and reduction of vectors there are 5 the first is the simple multiplication the second is the polygon method the third is the triangle method the fourth is the line method and the fifth is the Urayan method we will discuss one by one the 5 following methods starting from the first one first

which is the simple multiplication method. The simple multiplication method is specifically for the vector that is in the same direction. As an illustration, pay attention to the following image. We have two vectors, vector A and vector B. So we just need to unite the resultant vectors like this, with the same direction, but we combine the lengths. And mathematically, we can write the resultant similarity as vector A plus vector B. The second method is the polygon method.

The principle of the polygon method is that the point of the top meets the point of the end. Let's say we have four vectors like this. Vector A is to the right, Vector B is to the top, Vector C is also to the top to the left, and Vector D is to the left. Well, if we combine the vectors with the polygon method, it will be like this. So the end meets the top, and the resultant vector is from top A to the end of D.

And we can write mathematically, the resultant vector is equal to vector A plus vector B plus vector C plus vector D. Well, for the intersection, the direction is reversed. For example, vector A is directed to the right. If the vector A is intersected, it means the direction is to the left with the same length. Remember, the top meets the end. If the end meets the end, the sign will be negative. Next, the triangle method.

The third-row method is usually used to calculate the result or the mixture of vectors. As an illustration, pay attention to the following image. We have two vectors. The first vector is vector A, the second vector is vector B. We combine the end of vector A with the end of vector B. So the result is from the end of vector A to the end of vector B. And in this third-row, three angles are formed. Alpha here, beta here, and gamma here.

For example, the greater than the vector a is equal to a, the greater than the vector b is equal to b, then the resultant from vector a and b is a + b, and the intersection from vector a and b is a - b. Then the following formula will apply for the resultant. The resultant will be equal to the root of a squared plus b squared plus 2ab cos gamma, gamma is the angle of the arc between vector a and b. If it is intersected,

The difference is, if this is a plus sign, this is just a minus. Then there is the sine rule. Because this is a triangle, it forms three angles, then there is a sine rule whose function is to determine the direction of the vector if we use the triangle method. What is the sine rule? Well, mathematically we can write it like this. Per sin alpha, the angle that crosses with vector A, right? The angle of alpha. That will be equal to B. Per sin beta, the angle that crosses with vector B, right? Beta. Equal to R.

per sin gamma because the angle that crosses with the vector r is gamma like that. Next, the fourth method is the parallelogram method. The resultant vector in the parallelogram method is the diagonal, whose point of the axis is the same as the two vectors. As an illustration, for example we have two vectors like this, vector a and vector b, the angle is alpha. The resultant is just pull it

the line from the top of vector A and B, so we unite the top first, and if we project vector A upwards, it becomes this split line, and if we project vector B to the right, it looks like a line of lines. Well, for the intersection, the direction is reversed. If vector B, for example, the direction is upwards. If it's -B, it means that the same length, the direction is downwards. And the intersection between vector A and B is the direction downwards, like this. So this is equal to A-B.

The principle is the same, but if it is confused, the direction is reversed. Well, it's the same as the triangle method, for the line method, this cosine formula also applies. For example, the greater the vector A is A, the greater the vector B is B, the resultant is A + B, that is the greater the root of A^2 + B^2 + 2ab cos alpha, but if it is confused, we just have to replace the plus sign with a minus sign. And for the greater the resultant vector,

a vector has a result between the minimum result and the maximum result, where the minimum result is equal to the absolute from and the maximum result is equal to . This is for the case of two vectors, like that. Next, the fifth is the Urayan method.

Vector is defined by the components, the components x and y. For example, we have a vector that forms an alpha angle towards the positive source. The pattern is always positive here. If we declare a vector as a single vector, here it is axi + ayj. And to declare a vector as a single vector, for the x component, we declare it with i, and for the y component, we declare it with j.

We can also replace the Ax vector with A cos alpha, because A is attached to the Ax angle. Ax is attached to the angle. Ay is not attached to the angle. So we can replace the Ay vector with A sin alpha. From here we can determine the magnitude and direction of the vector. If we already have the x component and the y component, that's it. To determine the magnitude of the vector A, just like the Pythagorean theorem, this is equal to the root of Ax squared plus Ay squared, and for the direction,

or alpha here, we can find it by using hand comparisons, or tan alpha = Ay per Ax, so that the alpha is equal to tan inverse of Ay per Ax. Like that. Now, to make it clearer, let's just take a look at the following examples. The first example, two vectors, each 3 N and 7 N. The resultant of the two vectors cannot be worth a point. So how to solve a problem like this?

remember this formula, the resultant will be between R-min and R-max, where R-min is the same as the absolute of 3-min7, smaller than R, smaller than the absolute 3+7, so we subtract it, then we make it absolute, if the one on the left, we multiply it, then we give the sign of absolute, so min4 if we make it absolute, it becomes

If 13.7, it will be 10. So the resultant value may be between 4 and 10. But it is not allowed outside the interval of 4 to 10. So which one do you try? Between these 5 options. You know, of course, if 4 is possible, it's between 4 to 10. 5 is also possible. 6 is also possible. 7 is also possible. What is not possible is the A. The 3 N. Like that. The second example.

An ant moves from position A to position B as shown in the figure. The magnitude of the ant's movement is a point. If the movement is measured from the initial position to the final position. And if the angle is 60 degrees, remember that if the angle is straight, it means that the magnitude is 120 degrees. So the magnitude of the ant's movement is this one. We call it delta S.

So to calculate the magnitude of the S-relative, it is the same as the vector equation. This is the same as the root of a^2 + b^2 - 2ab cos alpha. Alpha is the angle of the arc between this 16 meters and this 16 meters. So we just replace a with 16, b with 16, cos alpha with cos 120. Substitute all of these to the equation. cos 120 is negative 1/2. So 16^2 + 16^2.

Minus 2 and minus half will be divided into plus 1 times 16 squared. So, there are 3 16 squared. If we take it out from the root, it will be 16 3 meters roots. So, the correct answer is B. That's it. The third example. Two vectors A and B form a 75 degree angle, and the resultant R forms a 30 degree angle towards vector A.

then the comparison of vector A and B is point by point. Well, let's first draw the vector A and B. This is a 75 degree angle, but the result is a 30 degree angle. So that we can find the comparison between vector A and vector B, here we can use the triangle method. How? We first move vector B to the end of vector A. So it's like this, friends. If we move vector B, it doesn't change the length and direction.

So, we just move the B here, the angle is still 75 degrees. So, this is in the shape of a triangle. If this is 75, because one angle is 180, then this is 105. This is 30 degrees. Why? Because it is known in the question. The vector A will form a 30 degree angle with the result here.

Then, the first triangle is 180, so this one is 45 degrees. Now it's easy if we want to find the comparison of vector A and vector B. How? Let's see, vector A is across the angle of what? 45 degrees, right? Vector B is across the angle of 30 degrees. And we know the angle of 45 degrees and angle of 30 degrees for the trigonometry comparison. So we can use the sine rule, namely,

per sin 45 degrees which is opposite, equals b per sin 30 degrees which is opposite. The question is just a comparison of the vector a and b, just change the position like this. So a per b equals sin 45 degrees per sin 30 degrees. Check in the trigonometric table, sin 45 what, sin 30 what, and

Sin 45 is half root of 2, sin 30 is half. We can subtract half of it. So later we get the comparison between the vectors A and B is root of 2 divided by 1. So the correct answer here is B. Like that. Example question number 4. Three factors of change, each of them is length A, this is 2, root of 2 meters. Length B is 6 meters, and length C is 4 meters.

as in the following image. Determine the result and the direction of the change to the three vectors. Well, how to solve the result of a vector of more than two? We define a vector that forms an angle towards the x-axis here. So the horizontal vector, we project it first to the x-axis and the y-axis. See, where is the horizontal? The B and the C, right? So if we define the B to the x-axis and the y-axis, it will be like this. This is 6.

We cut to the x-axis, so 6 cos 45, because it sticks to the 45 degree angle. In the y-axis, this is 6 sin 45 degrees. Which one is the opposite? The fourth, right? We cut the fourth here. So to the right, 4 cos 45, to the bottom, 4 sin 45. From here, we just focus on finding the total resultant vector in the x-axis and in the y-axis. How many times do we try in the x-axis?

There are 6 cos 45 and 4 cos 45. The 4 and 6 are just omitted, we have already divided them. So for sigma Rx, this is equal to 6 cos 45 plus 4 cos 45, added because they are in the same direction. All of them are on the same right. So this is equal to 10 cos 45. We replace cos 45 with half of the square root of 2. So if we calculate, the result will be 5 square root of 2. If we calculate the sum of y now,

At the Y-shape, there are 6 sin 45, there are 2 root 2, and there are 4 sin 45. But be careful, the 4 sin 45 is down, so it must be reduced later. So sigma RY = 2 root 2 + 6 sin 45 degrees, reduced by 4 sin 45 degrees. We replace the sin 45 with half root 2, then we just count it, later we get sigma RY = 3 root 2. We already have the vector component of the change in the direction of the X-shape and the Y-shape.

And to find the resultant magnitude, we just need to use Pythagoras. Sigma R equals the root of sigma Rx squared plus sigma Ry squared. That's the result we've got for this resultant magnitude. Like this. So we get sigma R equals 2 root 17 meters. And for the resultant direction, it means alpha equals tan inverse of sigma Ry per sigma Rx. What is sigma Ry? 3 root 2.

The sigma rx is 5x2, which means the sigma ry is positive towards the source y, and the sigma rx is positive towards the source x. If we calculate, we will get the result as tan inverse of 3x2/5x2. Calculate using a calculator, we will get the result as 30.96 degrees. That's all for this short discussion about the material and examples of physical factors in class 10.

Hopefully this video is useful and helps all of you in learning. Next, there are 4 exercises that you can try to do. Thank you for your attention. See you in my next video.