Answer: Option D Refer to the video for the explanation

Answer: Option A For such questions, always locate accurately the position of the image of the O. Then draw the ray from the image to the observer. To determine the maximum scope of view using the mirror, always use the two extreme edges of the mirror as point of incidences.

Answer: Option D The most common mistake is to equate total energy at X equals to total energy at Y. At Y, there is no way to know the speed as the speed varies which depends on the speed at X. Since the question wants to find the minimum speed at X to reach Y, you should focus on the highest point of the hill. If you can just clear the hill, you will sure reach Y. So you should consider the total energy at the highest point of the hill and assume the ball just barely reaches the top and stops there. Hence at the highest point, the energy of the ball is just GPE and you can find the minimum speed at point X. Any speed higher, you can clear the hill and reach Y.

Answer: Option B Refer to the video explanation

Answer: Option B To solve this question, you need to apply your FLHR. From the image, you will be able to know the orientation of the force F (thumb) and the magnetic field M (first finger). For the radiation path that goes straight, it indicates that it is not affected by the magnetic field. That means the radiation has no charge, hence it is gamma rays (a type of electromagnetic wave) For the radiation path that curves upwards, that means there is a force acting to the top of the image. So orientate the FLHR according and the 2nd finger (convention current) points to the right. Note the the direction of the convention current is the path in which a positive charge will take, so the radiation must be positive charge, i.e helium nucleus (alpha particles).

Answer: Option C For such questions, always look at the blocks as one single system and find the acceleration of the whole as one. That acceleration is the same for both blocks. Then apply free body diagram (the one with the unknown T and with the least number of forces acting), find the unknown T. Refer to this post for more examples of such questions (some involve friction) https://www.sgphysicstuition.com/post/finding-forces-on-multiple-bodies

Answer: Option A Once the water wave is produced, frequency of the wave remains constant even when it travels from deep to shallow or vice versa. Frequency depends on the source (i.e. the dipper which creates the ripples) Refer to the video explanation

Answer: Option D For total internal reflection TIR to occur, two conditions must be present: 1. light must be travelling from a optically denser medium towards an optically less dense medium. 2. the angle of incidence i is greater than the critical angle c Key things to take note: 1. The angles stated on the diagram are not angles of incidence. Angle of incidence is between the incident ray and the normal. 2. The diagram on the left is TIR as all the light is being internally reflected within the optical denser medium, which is the liquid. 3. The diagram on the right with refracted ray along the boundary, i.e. angle of refraction is 90 degrees, the angle of incidence now is also the critical angle of the liquid. Refer to the video explanation

Answer: Option A Refer to the video explanation

Answer: Option A Firstly, you need to know that at both pivot P and Q, there are normal contact forces acting upwards on the plank. 2 conditions for the plank to be in equilibrium: 1) Sum of clockwise moment = Sum of anticlockwise moment (POM) 2) Net force = 0N (i.e. total upward forces = total downward forces) To find the value of the normal force, you can choose to take pivot about either P or Q. If you take moment about P, the normal force at P will not be in the Principle of Moments equation Ma = Mc as the line of action of the normal contact forces at P passes through the pivot P, there is no perperdicular distance, hence no moment created. We can determine the value of the normal contact forces at Q. Once normal force at Q is found, you can use the concept net force = 0N to find the normal force at P straight away, which is faster.

Answer: Option D From the resultant force-time graph, from time to time 0 to t, there is a decreasing resultant force. Using Fnet = ma, as the Fnet decreases, the acceleration is decreasing. But note that decreasing acceleration does not mean speed is decreasing. It means the speed is still increasing, just that the increment is getting smaller per unit time. After time t, there is not resultant force, hence no acceleration. Since the object is already moving, it will continue to move at constant speed in a straight line. On the speed time graph, D fits the scenario.

Answer: Option A When there is current flowing through the wire, there is magnetic field generated around the wire. To determine the direction of the magnetic field, we can use Right Hand Grip Rule (RHGR). To help in the visualisation, we can also use the ‘dot’ and ‘cross’ to represent magnetic field coming out of the paper and into the paper respectively.