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Algebra, STD2 EQ-Bank 08 MC

The energy (\(E\)) required to heat water varies directly with the mass (\(m\)) of the water.

It takes 2100 joules of energy to heat 500 grams of water by 1°C.

Which equation represents the relationship between \(E\) and \(m\)?

  1. \(E = 4.2m\)
  2. \(E = 0.24m\)
  3. \(m = 4.2E\)
  4. \(m = 0.24E\)
Show Answers Only

\(A\)

Show Worked Solution

\(E \propto m\)

\(E=km\)

\(\text{When } E = 2100 \text{ and } m = 500:\)

\(2100\) \(=k \times 500\)
\(k\) \(=\dfrac{2100}{500}\)
\(k\) \(=4.2\)

  
\(\therefore\ E=4.2m\)

  
\(\Rightarrow A\)