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Plan: Use Q = m · c · ΔT three times. Hot casting cools ΔT_hot = 500°C -
Tf. Cold water and steel tank heat ΔT_cold = Tf - 25°C. Set Q from hot
casting cooling = Q from cold tank heating.
here
m_cast · c_steel · ΔT_hot = (m_tank · c_steel + m_water · c_water) · ΔT_cold
m_cast · c_steel · (500°C - Tf) = (m_tank · c_steel + m_water · c_water) · (Tf - 25°C)
2.5 kg · 0.50 kJ/(kg K°) · (500°C - Tf) = (5 kg· 0.50 kJ/(kg K°) + 40 kg· 4.18 kJ/(kg K°)) · (Tf - 25°C)
Solve for Tf, remember that K° = C° (i.e. for ΔT's) </span>
transformer makes use of mutual induction for its operation in which change in magnetic field in one coil due to variation of current , induces voltage in the other coil. so changing magnetic field in the primary coil is very much needed for the transformer. Alternating current is a current which varies with time , hence it is suitable to produce changing magnetic field in the primary coil. on the other hand , the direct current remains constant all the time. hence can not produce a changing magnetic field. so DC current is not useful for transformers.
Answer: False.
Explanation: The Earth rotates once per day in direction from East to West. The rotation of the Earth daily is responsible for day and night experienced, the areas of the Earth facing the Sun experiences day time while the areas of the Earth away from the Sun in the Earth's shadow experiences night time.
While the revolution of the Earth around the gives rise to a year, as it takes 365 days for the Earth to go round the sun.
You don't need to worry about the 10 year bit with this question. Just grab a calculator and divide 100/2, then the answer to that (50) by 2 etc and keep dividing by 2 until you get down to 6.25.
The answer ends up being 4 half lives :)
If you don't understand what a half life is please let me know :)
