A high-performance server processor is equipped with a failsafe cooling system. When the system is shut down at time t=0t = 0t=0 minutes, the processor temperature, θ∘C\theta^\circ\text{C}θ∘C, decreases at a rate proportional to the difference between the processor's current temperature and the ambient room temperature, which is a constant 25∘C25^\circ\text{C}25∘C.
Immediately upon shutdown, the processor is at 145∘C145^\circ\text{C}145∘C and its temperature is decreasing at a rate of 3∘C3^\circ\text{C}3∘C per minute.
Show that
dθdt=−0.025(θ−25) \frac{d\theta}{dt} = -0.025(\theta - 25) dtdθ=−0.025(θ−25)Solve the differential equation
dθdt=−0.025(θ−25) \frac{d\theta}{dt} = -0.025(\theta - 25) dtdθ=−0.025(θ−25)to find an expression for θ\thetaθ in terms of ttt.
Determine the time taken for the processor temperature to drop to 85∘C85^\circ\text{C}85∘C. Give your answer to the nearest minute.
92 exam-style questions on WJEC A Level Maths 4.6 Integration (A-level only), covering 4.6.1 Integration (A-level only) and 4.6.2 Integration (A-level only). Each one has a worked solution and a mark scheme showing where the marks go.