An experiment to measure the speed of sound was carried out. David, who is 200m from a large brick wall clapped two pieces of wood together many times, each time he heard the echo (reflected sound) he immediately clapped again. Maryam used a stopwatch to time how long it took for 10 claps and echos. Explain why they timed 10 clap/echoes and not just 1?

Atoaster oven has a resistive heating element. the average rate at which it dissipates energy as thermal energy is 1.00 \(\rm kw\). in the united states, emf amplitude in household circuits is \(\mathcal e_{\max}\) = 170 \({\rm \; v}\) and the \(\rm ac\) oscillation rate is 60 \(\rm hz\). part a what is the root-mean-square current through the heating element?