Which of the following statements about an apple falling from a tree is true? a) its kinetic energy decreases and its potential energy increases. b) its potential energy decreases and its kinetic energy increases. c) its kinetic and potential energies remain constant. d) its mechanical energy increases.

Work out sian speed for the first 30 minutes of her journey. give your answer in km/h.

Air initially at 0.75 bar, 1000 k, and occupying a volume of 0.12 m^3 undergoes two processes. process 1-2: the air is compressed isothermally until the volume is halved. process 2-3: the air undergoes a constant pressure process until the volume is halved again. assume ideal gas behavior. a) determine the mass of the air, in kg. b) the work and the heat transfer for each of the two processes, in kj. (100 kj = 1 bar . m^3)

What is the magnitude of the acceleration vector which causes a particle to move from velocity −5i−2j m/s to −6i+ 7j m/s in 8 seconds. answer in m/s.