An experimental physicist is using the trapezium rule to estimate the total impulse (the area under a force-time graph) for four different test engines over the interval 0≤t≤50 \le t \le 50≤t≤5. The force F(t)F(t)F(t) (in Newtons) for each engine is modeled by the following functions:
Engine A: F(t)=1.5t+20F(t) = 1.5t + 20F(t)=1.5t+20 Engine B: F(t)=0.4t2+10F(t) = 0.4t^2 + 10F(t)=0.4t2+10 Engine C: F(t)=6t+4F(t) = 6\sqrt{t+4}F(t)=6t+4 Engine D: F(t)=60t+3\displaystyle F(t) = \frac{60}{t+3}F(t)=t+360
Identify the engine model for which the trapezium rule will produce an underestimate of the actual impulse over this interval. Justify your answer by considering the concavity of the models.
137 exam-style questions on OCR (MEI) A Level Maths 1.10 Numerical Methods (A-level only), covering 1.10.1 Locate roots by change of sign (A-level only), 1.10.2 When change of sign methods fail (A-level only), 1.10.3 Fixed point iteration (A-level only), 1.10.4 Newton-Raphson method (A-level only), 1.10.5 Convergence of iterations (A-level only), 1.10.6 Trapezium rule (A-level only), 1.10.7 Upper and lower bounds using rectangles (A-level only), and 1.10.8 Numerical methods to solve problems (A-level only). Each one has a worked solution and a mark scheme showing where the marks go.