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- Thick Cables for High Power Electrical Appliances
High power electrical appliances are those which draws high current. The thinner the wire (smaller cross-sectional area), the higher the resistance of the cable which brings the current into the electrical appliances. More thermal energy will be generated due to this higher resistance in the cable. The cable might be too hot or catch fire. So it is advisable to have thicker cables for high power electrical appliance as thicker cables have lower resistance.
- Kinematics – Swimmer in river with current, find distance downstream
Solutions: Option B Without the current in the river, the time taken for the swimmer to reach Q is 50s. This is based on the vertical constant speed of 1.2 m/s and veritcal (width of river) distance. With the current, which is constant 1.0 m/s, the swimmer will be drifted downstream. But the time taken to reach R from P is still 50s. So with the same 50s, you can calculate the horizontal distance based on the horizontal current speed of 1.0 m/s.
- Kinematics – Two balls free-fall with different mass and height
Solutions: Option B Key concepts: Both balls are free-falling, hence both will experience the same acceleration due to gravity 10 m/s2.
- Kinematics Question – Using gradient and area under graph
Solutions: Option B
- Ball thrown vertically up from building and falls to ground
A rock is thrown vertically upwards with a velocity of 29.4 m/s from the top of a building 78.4 m high. After how long will the rock reach the ground below? (Take g = 10 m/s2) Many are familiar with calculation when ball is released from rest. This question involves ball being thrown upwards, and then it falls to the ground. To solve this question, just treat the motion as 2 separate parts. 1) Ball going up to max height, 2) Ball going down (similar to ball released from rest from highest point)
