3/28/2020 0 Comments SacsccsacTherefore, speed = length of the tape chosen Time interval for that length You are provided with a runway and a data-logging system with a motion sensor. Describe how you should use the apparatus to conduct an experiment to demonstrate the relationship between the net force and the acceleration of a trolley. You may use additional apparatus if necessary (5M) Adjust the runway for friction compensation (1 M) Pull a trolley down the runway using an elastic thread. Keep the extension of the elastic thread constant all the way.M) Record the motion ot the trolley wit data-logging system and find the acceleration of the trolley. (1 M) Repeat by pulling he trolley with 2, 3 and 4 identical elastic threads, side by side and extended by the same length as before. (1 M) From the experiment, it is found that the acceleration of the trolley is directly proportional to and in the same direction of the net force. (1 M) It is not preferable to carry an excessive amount of goods on the bicycle when he is riding in the street, why? (3M) The larger the mass, the larger the inertia the bicycle has. 1 M) By newton's second law of motion, the deceleration of the bicycle would become smaller when John applies the brake. (1 M) As a result, the stopping distance ncreases (1 M) So the chance of having an accident is larger. In supermarkets, bottled drinks are usually stored in refrigerators with shelves inclined at an angle B with the horizontal.Explain why there is such an arrangement. Also state the minimum angle required to achieve the purpose above. Given mass of a bottle ‘M', friction between a I-kg bottled drink and the inclined shelf is f'. 3M) If the bottled drinks are put on inclined shelves, they would slide down automatically when the first bottle is taken. It is more convenient for customers. (1 M) MgsinB > f (f/M9 (1M) Therefore, the least inclination angle is sinA-1 ( f/Mg). In some parts of the world, it is common for people to shoot firearms straight up into the air during celebrations. Falling bullets pose a significant danger to bystanders. As a bullet falls, its velocity increases until it reaches a constant terminal velocity. Explain, in terms of forces acting on the bullet, why this happens.Also, assume the air resistance is bv , derive the terminal kinetic energy of the bullet. (5M) As the bullet falls, its downward weight and the upward air resistance (or friction) are acting on it (1 M) Firstly the bullet accelerates. The air resistance opposing the motion of the bullet increases with its velocity. (1 M) Finally, its weight is balanced by the air resistance at a certain velocity. (1 M) As the net force acting on the bullet is zero, the bullet will continue to fall at this constant velocity which is called terminal velocity. mg = bv) (1M) KE=O. 5mv?2 = 0. 5mA3 g,N2 /bA2 (1M) A basketball player Jumps up such that his height reaches a height of 3m. Using Newton's laws of motion, explain why the player can gain an initial speed to leave the ground vertically. (3M) The player exerts a force onto the ground when he is about to ump. (1 M)This results an equal normal reaction force from the ground according to Newton's 3rd law of motion. (1 M) As the normal reaction force is greater than the weight , the player will be forced to accelerate up according to Newton's 2nd law of motion. 1 M) Chapter 8 What is the advantage ot using the spanner„3z to turn a screw* effort(force) required can be reduced. (2) The efficiency can be increased. X (3) The energy required can be reduced. X For (2) and (3), they are wrong as moment is not related to energy. (Force is perpendicular to the displacement, the work done should be zero. ) Chapter 9 There are two methods of raising the block from the ground to a certain height. (2M) Method 1 : Pulling the block up a inclined plane Method 2 : Lifting the block vertically upwards.Method 1 is better than method 2 in terms of forces as smaller force is needed to raise the block in method 1. (1 M) However, method 1 has a lower efficiency because some energy is lost in overcoming the friction between the block and the plane. (1 M) What are the functions of the counterweight in a lift system? (3M) To reduce the power required to raise the car (1 M) To reduce the load acting on the motor (1 M) To improve the efficiency of the lift (As less energy is lost to overcome the friction between the cable line and the drum) (1 M) Verify the conservation of mechanical energy.Given a simple pendulum, a protractor, a light gate, a ruler. (7M) Set up a simple pendulum, a protractor and a light gate. (1 M) Displace the bob and read the angle B between the string and the vertical from the protractor. (1 M) Start data-logging and release the bob. (1 M) Record the time t taken for the bob to pass through the light gate. Measure the diameter of the bob(this is the distance travelled by the bob while passing the light ate, which is very small so the instantaneous speed of the bob in the lowest position calculated is relatively accurate), and hence estimate the speed v of the bob at the lowest position. 1 M) Use a ruler to measure the length I of the pendulum. Apply the conservation of mechanical energy and calculate the speed v of the bob at the lowest position. (1 M) V = {square root (2gh)} , where h = I(1-cosB) (1 M) Conclusion, the two values of speed calculated is quite close so the law of conservation of energy is proved.
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1/18/2020 0 Comments A History of God : The 4,000-Year Quest of Judaism, Christianity and Islam by Armstrong, KarenThe writing of Karen Armstrong actually notes the human views of the existence of God in three major designs of religious belief in the society today, namely that of the Judaism, Christianity and Islam.One reason is that the roots of the Jewish religion go back some 4,000 years in history and other major religions are indebted to its Scriptures to a greater or lesser degree. Christianity, founded by Jesus (Hebrew, Ye‧shu′a‛), a first-century Jew, has its roots in the Hebrew Scriptures. And as any reading of the Qur’Än will show, IslÄm also owes much to those scriptures. (Qur’Än, surah 2:49-57; 32:23, 24) Thus, when we examine the Jewish religion, it could be noted that the roots of other religions are well examined just the same.Simply put, Judaism is the religion of a people. Therefore, a convert becomes part of the Jewish people as well as the Jewish religion. It is a monotheistic religion in the strictest sense and holds that God intervenes in human history, especially in relation to the Jews. Jewish worship involves several annual festivals and various customs. (See box, pages 230-1.) Although there are no creeds or dogmas accepted by all Jews, the confession of the oneness of God as expressed in the Shema, a prayer based on Deuteronomy 6:4 (JP), forms a central part of synagogue worship: “HEAR, O ISRAEL: THE LORD OUR GOD, THE LORD IS ONE.â€This belief in one God was passed on to Christianity and IslÄm. According to Armstrong: “This sublime pronouncement of absolute monotheism was a declaration of war against all polytheism . . . In the same way, the Shema excludes the trinity of the Christian creed as a violation of the Unity of God.†The three major monotheistic religions of the world are Judaism, Christianity, and IslÄm.But by the time Muḥammad appeared toward the beginning of the seventh century C.E., the first two religions, as far as he was concerned, had wandered from the path of truth. In fact, according to some IslÄmic commentators, the Qur’Än implies rejection of Jews and of Christians in stating: “Not (the path) of those who earn Thine anger nor of those who go astray.†(Surah 1:7, MMP) Why is that?A Qur’Änic commentary states: “The People of the Book went wrong: The Jews in breaking their Covenant, and slandering Mary and Jesus . . . and the Christians in raising Jesus the Apostle to equality with God†by means of the Trinity doctrine.—Surah 4:153-176, AYA. The principal teaching of IslÄm, for utter simplicity, is what is known as the shahÄdah, or confession of faith, which every Muslim knows by heart: “La ilÄh illa AllÄh; Muḥammad rasÅ«l AllÄh†(No god but Allah; Muḥammad is the messenger of Allah). This agrees with the Qur’Änic expression, “Your God is One God; there is no God save Him, the Beneficent, the Merciful.â€(Surah 2:163, MMP) This thought was stated 2,000 years earlier with the ancient call to Israel: “Listen, O Israel: Jehovah our God is one Jehovah.†(Deuteronomy 6:4) Jesus repeated this foremost command, which is recorded at Mark 12:29, about 600 years before Muḥammad, and nowhere did Jesus claim to be God or to be equal to Him.—Mark 13:32; John 14:28; 1 Corinthians 15:28. Regarding God’s uniqueness, the Qur’Än states: “So believe in God and His apostles. Say not ‘Trinity’: desist: it will be better for you: for God is One God.â€(Surah 4:171, AYA)However, we should note that true Christianity does not teach a Trinity. That is a doctrine of pagan origin introduced by apostates of Christendom after the death of Christ and the apostles.
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