Question 20
Quantity of HeatA 500 W heater is used to heat 0.6 kg of water from 25 °C to 100 °C in t1 seconds. If another 1000 W heater is used to heat 0.2 kg of water from 10 °C to 100 °C in t2 seconds, find t1/t2.
- A.50
- B.5
- C.5/4
- D.1/5
Show the answer and explanation
Answer: B (5)
Explanation
t = mcΔθ/P. t1 = 0.6 × c × 75/500 = 0.09c and t2 = 0.2 × c × 90/1000 = 0.018c, so t1/t2 = 5.