FISIKA DASAR By: Mohammad Faizun, S.T., M.Eng. Head of Manufacture System Laboratory Mechanical Engineering Department Universitas Islam Indonesia

Kinematika 1 (Dimensi I) REFERENCES: 1. Halliday, D.A., and Robert Resnick, 2. Alonso, M., Fundamental University Physics, Erlanga: 1990. 3. Giancoli, Fisika Jilid I, Erlangga, 1998. 4. Sears, F.W. and M.W. Zemansky, University Physics, 12 Edition, Pearson: 2007. 5. http://www.saskschools.ca/curr_content/physics30/kindyn/lessoni_1_1.html

A. RELATIVE POSITION You want to go to Mira house, but you never go to there yet. Now you are lost. Then you meet with two people and ask them to give you a clue. Here are their answers: First man : Mira house is 2 km from here. Second man :You just go straight to west about and you will find “SMART” supermarket. Mira house is the fifth house behind the supermarket, the yard is green. First answer make you still confused. The second answer is very clear and you will arrived at Mira’s hous soon. In this case “SMART” supermarket become a refference point. Relative position of Mira’s house is fifth house behind the “SMART” supermarket.

The components of relative position is: Reference point, for example: here, Jogja, Post office, etc. direction, for example: north, south, behind, up, etc. distance, for example: 2 km, 100 m, 20 cm, etc.

Exercise: Show the refference point and components of these relative position if it’s possible: Klaten is 20 km north of Jogja. The car moves forward 200 meters. Tina is now about 2 meter behind Andi. Solo is in Central Java. Semarang is the capital city of Central Java.

Relative position in number line. Reference point in number line is point O. Reference point is not always at center point. The relative position of A is written: . For example here: = -3 cm. = 4 cm. Negative value mean it is in left side from the reference point, i.e. point O. Positive value mean it is in right side from the reference point, i.e. point O. This is internationally accepted. So, negative or positive sign shows the direction and 3 cm or 4 cm shows the distance. 4 1 2 3 -4 -3 -2 -1 cm O A B

Please determine the relative position of A, B, and C! Exercise. Please determine the relative position of A, B, and C! first number line, second number line, 4 1 2 3 -4 -3 -2 -1 km C A B North South 4 1 2 3 mil C A B west east 5 6 7 8

You can set the reference point arbitrarily. This is an example You can set the reference point arbitrarily. This is an example. Andi stands 2 meter in front of me. Bagyo stands 3 meters behind me. If you set myself become the reference point then you will get number line like this. = 0 m. = -3 m. = 2m. 3 m 2 m 4 -3 m Bagyo front behind me Andi

Please determine the relative position of me, Andi, and Bagyo! If we set bagyo to become the reference point then you will get the number line as below. Please determine the relative position of me, Andi, and Bagyo! 5 3 m Bagyo front behind me Andi

B. JARAK, PERPINDAHAN, DAN PANJANG LINTASAN Jarak (distance) : adalah panjang dari sebuah garis lurus yang menghubungkan dua titik. Perpindahan (displacement): adalah jarak antara posisi awal dan posisi akhir. Panjang lintasan (length of the path): adalah panjang lintasan yang ditempuh. Panjang lintasan lintasan

Contoh lain: jarak titik C dan D adalah 3 meter. Contoh JARAK (d): Pancang A dan pancang B dipasang pada sebuah sungai dengan alur seperti gambar berikut. Jarak antara pancang A dan pancang B adalah panjang garis yang ditarik lurus dari A menuju B, yakni 5 meter. Contoh lain: jarak titik C dan D adalah 3 meter. 5 m A B D C 3 m

Contoh PERPINDAHAN ( ) Seekor semut bergerak dengan lintasan seperti pada gambar berikut. Tentukan besarnya perpindahan dari semut tersebut. Jawab besarnya perpindahan semut tersebut sama dengan panjang A-A’, yakni: Y(m) X (m) 1 2 3 -3 -2 -1 A A’ m m m

Contoh PANJANG LINTASAN ( s ) Seekor semut bergerak dengan lintasan setengah lingkaran seperti pada gambar berikut. Tentukan besarnya panjang lintasan dan perpindahan dari semut tersebut. Jawab panjang lintasan semut tersebut sama dengan panjang busur A-B, yakni: R=10 m A B Besarnya perpindahan semut tersebut sama dengan panjang garis yang menghubungkan A dan B yakni 20 meter.

Question?