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1 markSpecific Latent Heat, l

CSEC Physics · 1997 · Paper 2 · Question 4(b)(v)

Inside a pressure cooker, the pressure is higher than normal. Figure 10 shows the pressure cooker being used to cook some food. The lid is airtight except for a small hole, which has an area of 1 x 10⁻⁵ m², at the top. A weight is placed on top of the hole to close it.

To prevent accidents, the safety valve opens if the pressure inside the pressure cooker exceeds twice the pressure of the atmosphere. At what temperature does this occur?

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Other parts of this question

  1. 4(a)(i)At what temperature would you expect water to boil?[1 mark]
  2. 4(a)(ii)What TWO factors lead to the pressure being lower at greater altitudes?[2 marks]
  3. 4(b)(i)If the weight used is 0.5 N, what is the pressure due to this weight? Convert your answer to kPa.[4 marks]
  4. 4(b)(ii)What is the total pressure acting on the contents if atmospheric pressure is 100 kPa?[1 mark]
  5. 4(b)(iii)At what temperature would the water in the pressure cooker boil?[1 mark]
  6. 4(b)(iv)What effect might the temperature identified in (iii) above have on the time it takes for the food to cook?[1 mark]
  7. 4(c)In terms of the kinetic theory of gases, why does the pressure of the gas in a sealed container rise when the temperature rises?[3 marks]

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