Atoy car moves around a circular track at constant speed. it suddenly doubles its speed — a change of a factor of 2. as a result, the centripetal acceleration changes by a factor of (a) 1/2.(b) 4.(c) no change since the radius doesn't change.(d) 2.(e) 1/4.

Along wire of diameter 1 mm is submerged in an oil bath of temperature ∞ 31°c. the wire has an electrical resistance per unit length of 0.01 ω/m. if a current of 103 a flows through the wire and the convection coefficient is 500 w/m2·k, what is the steady-state temperature of the wire? from the time the current is applied, how long does it take for the wire to reach a temperature that is within 1°c of the steady-state value? the properties of the wire are 8000 kg/m3, 500 j/kg·k, and 20 w/m·k.