Finding quadratic constants from real-world trajectory or context

Determine unknown constants in a quadratic model arising from a real-world context (e.g. trajectory of a ball, exchange rate model) where conditions are given via a described physical situation or graph of a trajectory.

4 questions · Moderate -0.0

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Edexcel AS Paper 1 2020 June Q14
9 marks Standard +0.8
  1. A curve has equation \(y = \mathrm { g } ( x )\).
Given that
  • \(\mathrm { g } ( x )\) is a cubic expression in which the coefficient of \(x ^ { 3 }\) is equal to the coefficient of \(x\)
  • the curve with equation \(y = \mathrm { g } ( x )\) passes through the origin
  • the curve with equation \(y = \mathrm { g } ( x )\) has a stationary point at \(( 2,9 )\)
    1. find \(\mathrm { g } ( x )\),
    2. prove that the stationary point at \(( 2,9 )\) is a maximum.
Edexcel Paper 1 2021 October Q12
9 marks Moderate -0.3
12. \begin{figure}[h]
\includegraphics[alt={},max width=\textwidth]{08ede5ea-85e9-44eb-be6a-5878096734e2-38_666_1189_244_440} \captionsetup{labelformat=empty} \caption{Figure 3}
\end{figure} Figure 3 is a graph of the trajectory of a golf ball after the ball has been hit until it first hits the ground. The vertical height, \(H\) metres, of the ball above the ground has been plotted against the horizontal distance travelled, \(x\) metres, measured from where the ball was hit. The ball is modelled as a particle travelling in a vertical plane above horizontal ground.
Given that the ball
  • is hit from a point on the top of a platform of vertical height 3 m above the ground
  • reaches its maximum vertical height after travelling a horizontal distance of 90 m
  • is at a vertical height of 27 m above the ground after travelling a horizontal distance of 120 m
Given also that \(H\) is modelled as a quadratic function in \(x\)
  1. find \(H\) in terms of \(x\)
  2. Hence find, according to the model,
    1. the maximum vertical height of the ball above the ground,
    2. the horizontal distance travelled by the ball, from when it was hit to when it first hits the ground, giving your answer to the nearest metre.
  3. The possible effects of wind or air resistance are two limitations of the model. Give one other limitation of this model.
Edexcel Paper 2 2024 June Q9
7 marks Moderate -0.3
9. \begin{figure}[h]
\includegraphics[alt={},max width=\textwidth]{2ce10759-9ce6-47a1-b55d-d22082f88f55-22_595_1058_248_466} \captionsetup{labelformat=empty} \caption{Figure 3}
\end{figure} The graph in Figure 3 shows the path of a small ball.
The ball travels in a vertical plane above horizontal ground.
The ball is thrown from the point represented by \(A\) and caught at the point represented by \(B\). The height, \(H\) metres, of the ball above the ground has been plotted against the horizontal distance, \(x\) metres, measured from the point where the ball was thrown. With respect to a fixed origin \(O\), the point \(A\) has coordinates \(( 0,2 )\) and the point \(B\) has coordinates (20, 0.8), as shown in Figure 3. The ball reaches its maximum height when \(x = 9\) A quadratic function, linking \(H\) with \(x\), is used to model the path of the ball.
  1. Find \(H\) in terms of \(x\).
  2. Give one limitation of the model. Chandra is standing directly under the path of the ball at a point 16 m horizontally from \(O\). Chandra can catch the ball if the ball is less than 2.5 m above the ground.
  3. Use the model to determine if Chandra can catch the ball.
OCR MEI AS Paper 2 2023 June Q15
7 marks Moderate -0.3
15 A family is planning a holiday in Europe. They need to buy some euros before they go. The exchange rate, \(y\), is the number of euros they can buy per pound. They believe that the exchange rate may be modelled by the formula \(y = a t ^ { 2 } + b t + c\),
where \(t\) is the time in days from when they first check the exchange rate.
Initially, when \(t = 0\), the exchange rate is 1.14 .
  1. Write down the value of \(c\). When \(t = 2 , y = 1.20\) and when \(t = 4 , y = 1.25\).
  2. Calculate the values of \(a\) and \(b\). The family will only buy their euros when their model predicts an exchange rate of at least 1.29 .
  3. Determine the range of values of \(t\) for which, according to their model, they will buy their euros.
  4. Explain why the family's model is not viable in the long run.