When oxygen reacts with hydrogen, it has the capacity to release 29 kilojoules of energy. inside a fuel cell, oxygen reacts with hydrogen to produce 23 kilojoules of useful energy. the rest of the energy is lost as heat. what’s the efficiency percentage of the fuel cell?

Aperson gives a shopping cart an initial push along a horizontal floor to get it moving, and then lets go. the cart travels forward along the floor, gradually slowing as it moves. consider the horizontal force(s) on the cart while it is moving forward and slowing. which of the following statements is correct? (a) both a forward and a backward force are acting on the cart, but the forward force is larger. (b) only a forward force is acting which diminishes with time. (c) both a forward and a backward force are acting on the cart, but the backward force is larger. (d) only a backward force is acting, no forward force.

En un laboratorio, nakisha mezcla una solución de hidróxido de sodio con un indicador llamado fenolftaleína. cuando se combinan, crean una solución de color rosa. nakisha se pregunta si la mezcla de otras soluciones con fenolftaleína también creará este color rosa. ? cómo podría nakisha utilizar el proceso de investigación científica para determinar si la mezcla de otras soluciones con fenolftaleína también creará un color rosa? marque las que correspondan.

How many meters will a car travel if its speed is 45 m/s in an interval of 11 seconds? question 2 options: a) 450 meters b) 495 meters c) 4.09 meters d) 498 meters