A box sitting still on the ground by itself has a Normal Force of 980N, what is the mass? (gravity's acceleration is -9.80 m/s^2 or 9.80 m/s^2 downwards) ​

Could someone . i have tried to solve myself but my calculation is off

Contains chemical energy. a. heat b. light c. natural gas

An ideal otto cycle has a compression ratio of 8. at the beginning of the compression process, air is at 95 kpa and 27°c, and 750 kj/kg of heat is transferred to air during the constant-volume heat-addition process. assuming constant specific heats at room temperature, determine (a) the pressure and temperature at the end of the heat-addition process, (b) the net work output, (c) the thermal efficiency, and (d) the mean effective pressure for the cycle. (4390 kpa, 1730 k; 423 kj/kg; 56.4%; 534 kpa)