An electroplating bath, as shown in Figure 1.1, is used to plate silver uniformly onto objects such as kitchenware and plates. During the process, each coulomb transports 1.2mg of silver. The voltage across the element is a constant of 240 V. For each object, it takes 25 seconds to complete and the current entering the terminal of the object is as shown in Figure 1.2. Assume that q(t)=0 for t<0. 1) Find the charge q(t) and sketch its waveform for t≥0; (10%) 2) If 3,600 objects are plated and the electric energy costs 30c/kWh, please determine the cost to complete the work. (8%) 3) What is the weight of silver deposited on one plate in grams for 25 seconds? (4%)