> en cual de las siguientes situaciones la fuerza neta sobre el cuerpo es cero? 1. un avion que vuela al norte con rapidez constante de 120 m/s y altitud constante; 2. un automovil que sube en linea recta por una colina con pendiente de 3 grados, a una rapidez constante de 90 km/h; 3. un halcon que vuela en circulos con rapidez constante de 20 km/h a una altura constante de 15 m a campo abierto; 4. una caja con supercies lisas, sin friccion, que esta en la parte de atras de un camion cuando este acelera hacia adelante en un camino plano a 5 m/s2.

A1kg cart slams into a stationary 1kg cart at 2 m/s. the carts stick together and move forward at a speed of 1 m/sl. determine whether kinetic energy was conserved in the collision. use the law of conservation of energy to explain the collision

These models show the electron structures of two different nonmetal elements. which element is likely more reactive, and why? element 1 is more reactive because it has fewer electron shells and is toward the top of its group on the periodic table. element 1 is more reactive because it has more electrons in its valence shell and is farther to the right on the periodic table. element 2 is more reactive because it does not have a valence shell close to the nucleus, so it will attract electrons. element 2 is more reactive because it does not have a full valence shell, so it will attract electrons.

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.