2025 AMKSS Pure Physics Prelim P2 + MS

2 AMKSS 4E PRELIM Exam 6091(Revised)/02/2025 Answer all the questions. 1. Fig 1.1 shows a uniform beam which is supported by two light cables, AB and AC. They are attached to a vertical steel cable from a crane. The beam is at rest. Fig 1.1 (a) Explain why the centre of gravity of the beam shown in Fig 1.1 must be vertically below A when the beam is at rest. ……………………………………………………………………………………………………… ……………………………………………………………………………………………………[2] (b) A student made this statement: “The tension in the vertical steel cable and the weight of the beam are an action and reaction pair of forces.” Explain with two reasons if you agree or disagree with the statement. ……………………………………………………………………………………………………… ……………………………………………………………………………………………………… ……………………………………………………………………………………………………[2] (c) State the two conditions for a system in equilibrium. ……………………………………………………………………………………………………… ……………………………………………………………………………………………………… ……………………………………………………………………………………………..……..[2] 2025 Phy Set 5

3 AMKSS 4E PRELIM Exam 6091(Revised)/02/2025 [Turn Over 2. A student with a weight of 500 N moves down a long slide as shown in Fig 2.1 on earth. Fig 2.1 The student moves from rest from X which is located at the top end of the slide. The surface of the slide is rough. He experiences an average resistive force of 70 N as he slides from X to Y. The kinetic energy of the student at Y is 300 J. The decrease in the gravitational potential energy of the student as he moves from X to Y is 3000 J. (a) State the law of conservation of energy. ……………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………[2] (b) Obtain the mass of the student. mass=……………..[1] (c) Determine the speed of the student at Y. speed=……………………..[2] (d) Calculate the length of the slide. You may assume that the air resistance experienced by the student while sliding from X to Y is negligible. length of the slide=………………………….[2]

4 AMKSS 4E PRELIM Exam 6091(Revised)/02/2025 (e) At end Y of the slide, the student is brought to rest by a board as shown in Fig 2.2. Fig 2.2 A spring connects the board to a fixed point. The student hits the board so that it moves to the right and compresses the spring. The speed of the student becomes zero when the elastic potential energy of the spring has increased to its maximum value of 140 J. Calculate the percentage efficiency of the transfer of the kinetic energy of the child at Y to the elastic potential energy of the spring. percentage efficiency=……………………………..[1] 3. A uniform plank of length 4.00 m and weight 800 N is suspended by two strings at X and Y from the ceiling as shown in Fig 3.1. A box of 2.5 kg is placed on the plank. Fig 3.1 (a) Label clearly the following forces on Fig 3.1. (i) Weight of plank (Wplank) (ii) Weight of the box (Wbox) (iii) Tension in X(Tx) (iv) Tension in Y(Ty) [2] box

5 AMKSS 4E PRELIM Exa