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- Identification of which radioactive emissions
Answer: Option C
- Two parallel current-carrying wires with current in the same direction.
Answer: Option D Think of the lovers analogy. When both currents are in the same direction, it’s like couple in love, so attraction. Likewise, when the currents are in opposite direction, they quarrel, hence repulsion. On the magnitude of the force, always remember for electric force, magnetic force or gravitational force between objects, the forces are equal and opposite, action-reaction pair (Newton’s 3rd Law).
- What is the acceleration just before and after the ball hits the floor?
Answer: Option D Under free-fall, where there is no air resistance, when you release the ball or throw a ball up, the moment the ball leaves your hand, the only force acting on the ball is its weight and the acceleration is a constant 10 m/s^2 and is downwards, towards the centre of the Earth.
- What is the heat capacity of the beaker? (Pure Physics)
Answer: Option A Heat capacity (C) is the thermal energy transferred to increase the temperature of the substance by 1 oC or 1 K. Specific heat capacity (c) is the thermal energy transferred to increase the temperature of 1 kg of substance by 1 oC or 1 K. The relationship is C = mc i.e. the mass of the beaker is not given as the heat capacity already has taken into account the mass.
- What is the average force acting on the dart? Using COE and Kinematics to solve.
Answer: Option B This question can be solved using both Conservation of Energy and Kinematics. Indeed, using COE to solve will be much simpler and straight forward. But do know both methods.
- What is the speed of the train when it is 175 m from the station? (3 methods to solve)
Answer: Option D For this question, I will show you 3 methods to solve. What if the options are not given? The speed and time when the distance is 175 m will be unknown. And based on the basic concepts you learned in speed-time graph, you can form two equations to solve for the unknown speed and time. 1) gradient = acceleration and 2) area under= distance travelled. Some students asked about using the formula v^2 = u^2 + 2as. Though it is not in the syllabus, you can use it if you know the formula well, though many students just apply blindly. It is good to use the basic concepts you learned in the syllabus to solve. View the video
- What is the pressure at X? (Liquid pressure, Pure Physics)
Answer: Option A View the explanation
- Which radioactive source(s) produced these results?
Answer: Option C View explanation
- What is the resistivity of the material?
Answer: Option A
