Which of the following examples describes mechanical efficiency? A. greasing a surface helps reduce friction
OB. a longer lever helps lift more weight
O C. a fixed pulley changes the direction you
pull
D. pushing the object down a slope is less
work

Suppose while hauling rocks, you accidentally drop one. it breaks apart in flat, planar sections. what type of rock did you just drop? 20 points

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.

An airplane is flying with a velocity of 240 m/s at an angle of 30.0∘ with the horizontal, as the drawing shows. when the altitude of the plane is 2.4km,a flare is released from the plane. the flare hits the target on the ground. what is the angle θ?