In each case, lifting or pushing, why must you exert a force to move the object? q1-2: how much more effort is required to lift or push two bricks or masses instead of just one?

The earth is constantly spinning on its axis, like you might spin a basketball on your finger. it is this spinning of the earth that causes

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)

What is the largest meteoroid that has collided with this planet