A football running back of mass 90 kg moving at 5 m/s (positive direction) is tackled head on by another player of mass 120 kg running -4 m/s. They stick together. What is their final combined speed and direction (negative or positive sign)?

Select the correct answer. what does the process of natural selection involve?

Which of the choices are parts of an atom? select all that apply. a.) compound b.) electron c.) neutron d.) molecule e.) photon f.) proton g.) element

Two kilograms of air within a piston–cylinder assembly executes a carnot power cycle with maximum and minimum temperatures of 800 k and 300 k, respectively. the heat transfer to the air during the isothermal expansion is 60 kj. at the end of the isothermal expansion the volume is 0.4 m3. assume the ideal gas model for the air. determine the thermal efficiency, the volume at the beginning of the isothermal expansion, in m3, and the work during the adiabatic expansion, in kj.