A kettle is used to heat water - Edexcel - GCSE Physics - Question 8 - 2020 - Paper 1

Identify the coordinates of the points where the tangent intersects the graph. For example, you might estimate two points, such as (60, 60) and (150, 92).

To find the gradient (rate of increase in temperature), use the formula for gradient:

$ext{Gradient} = \frac{\text{change in temperature}}{\text{change in time}}$

Substituting the values: $\text{Gradient} = \frac{92 - 60}{150 - 60} = \frac{32}{90} \approx 0.356$

Therefore, the rate of increase in temperature at 150 s is approximately $0.36 \, \text{°C/s}$.