¿Por qué un niño en un carrito parece caer hacía atrás cuando el carrito se le da un súbito empujón hacía delante?

What accounts for an increase in the temperature of a gas that is kept at constant volume? a. energy has been removed as heat from the gas. b. energy has been added as heat to the gas. c. energy has been removed as work done by the gas. d. energy has been added as work done by the gas.