A2.8-kg physics cart is moving forward with a speed of 45 cm/s. a 1.9-kg brick is dropped from rest and lands on the cart. the cart and brick move together across the horizontal surface. assume an isolated system. what equation do i use to figure out the the final valocity

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.