Numerical Algorithm Development · IZhO 2021 #2

Physics · mechanics

Problem

In a computer experiment, the main idea of numerical calculations is to divide the trajectory of motion into small sections, in which the motion is described approximately. We divide the interval of motion from ϕ=ϕ0\phi = \phi_0 to ϕ=0\phi = 0 into NN equal intervals of width Δϕ\Delta\phi. Let us denote the splitting points as ϕk\phi_k, k=0,1,...Nk = 0, 1, ...N and the angular velocities at these points as ωk\omega_k. The main approximation used in further calculations is that at each interval from ϕk\phi_k to ϕk+1\phi_{k+1} the motion of the pendulum is considered uniformly accelerated. For a given amplitude ϕ0\phi_0 and the number of partition intervals NN, answer the following questions: 2.1 Determine the partition interval Δϕ\Delta\phi. 2.2 Determine the coordinates of the splitting points ϕk\phi_k. 2.3 Express the angular velocity ωk\omega_k at the point ϕk\phi_k at an arbitrary initial angle of deflection ϕ0\phi_0. Write down this formula for a particular case of ϕ0=π2\phi_0 = \frac{\pi}{2}. 2.4 Determine the travel time Δtk\Delta t_k for the k-th interval from ϕk\phi_k to ϕk−1\phi_{k-1}. 2.5 Find an expression for the time tkt_k it takes the ball to reach the angle ϕk\phi_k. To simplify matters, express it in terms of the travel time tk−1t_{k-1} to the previous value of the angle ϕk−1\phi_{k-1}. 2.6 Put down a formula for the oscillation period TNT_N for a given split into intervals. ATTENTION! Use the dimensionless quantities introduced in problem 1: time τ\tau, period T~\tilde{T} and angular velocity ω~\tilde{\omega}, which are denoted as tt, TT and ω\omega.

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