1. A 0.150-kg baseball moving at a speed of 45.0 m/s crosses the plate and strikes the 0.250-kg catcher's mitt (originally at rest). The catcher's mitt immediately recoils backwards (at the same speed as the ball) before the catcher applies an external force to stop its momentum. a. Determine the post-collision velocity of the mitt and ball.
b. Solve for the total kinetic energy before and after collision.

Scout feels ill one day before school. her mother puts a thermometer in her mouth and the temperature begins to climb to 100°f. what is happening between the cooler thermometer and scout's body? a) scout's body is applying a force to the particles in the thermometer. b) kinetic energy is being transferred from her mouth to the thermometer. c) potential energy is being lost by the thermometer and gained by scout's body. d) the potential energy stored in foods is converted to mechanical energy to raise the mercury in the thermometer.

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)

In a classical model of the hydrogen atom, the electron moves around the proton in a circular orbit of radius 0.053 nm. what is the electron's orbital frequency? what is the effective current of the electron?