A boy is riding a sled down a snow covered hill. A girl then jumps onto the sled as it is riding down the hill. Briefly explain what will happen to the (i) coefficient of friction when she jumps on and (ii) the force of friction when she jumps on.

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?