JPJC 2026 Energy and Fields Assignment

2026/JPJC/PHYSICS/9478 1 JURONG PIONEER JUNIOR COLLEGE 9478 H2 PHYSICS ENERGY AND FIELDS ASSIGNMENT 1 As a simple pendulum swings back and forth, the forces acting on the suspended object are gravitational force, the tension in the supporting cord, and air resistance. (a) Identify any force that does no work on the pendulum. Explain your answer. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. …………………………………………………………………………………………..…. [2] (b) Identify any force that does negative work at all times during the pendulum’s motion. Explain your answer. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ……………………………………………………………………………………………… [2] (c) Describe the work done by gravitational force while the pendulum is swinging. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………..…………….. [2]

2026/JPJC/PHYSICS/9478 2 2 A toy car of mass 0.2 0 kg is launched by means of a spring of spring constant 25 N m−1 as shown below. (a) The spring is compressed from its original length of 6.0 cm to 2.0 cm by the toy car. Determine the maximum distance covered by the toy car along the slope . State any assumption that you have made. [4] (b) If a motor is used to power the toy car such that it can travel up the slope at a constant speed of 4.0 m s−1, calculate the minimum power the motor must deliver. Explain your working. [3] toy car spring 30°

2026/JPJC/PHYSICS/9478 3 3 The Earth and the Moon may be considered to be spheres that are isolated in space with their masses concentrated at their centres. The masses of the Earth and the Moon are 246.0 10 kg and 227.4 10 kg respectively. The radius of the Earth is RE and the separation of the centres of the Earth and the Moon is 60RE, as shown in Fig. 3.1. Fig. 3.1 (a) Explain why there is a point between the Earth and the Moon at which the gravitational field strength is zero. …………………………………………………………………………………………………. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ……………………………………………………………………………………………… [2] (b) Determine the distance, in terms of RE, from the centre of the Earth at which the gravitational field strength is zero. [2] 60RE RE Earth mass Moon mass

2026/JPJC/PHYSICS/9478 4 4 Fig. 4.1 shows two positive charges q1 and q2 fixed to a circle. At the centre of the circle, they produce a net electric field that is directed upwards along the vertical axis. Fig. 4.1 Determine the ratio 1 2 q q . Explain your working. [3]