Explain one way in which friction actually helps people

The variables for this experiment include mass, volume and the materials in the various balls, as well as their densities. in part iii, you will be investigating the questionable baseball. use the drop-down menus to complete the sentences and identify the independent and dependent variables. in part iii, the independent variable, the one that is intentionally manipulated, is . in part iii, the dependent variable, the one that you measure the response in, is

Which of the following are properties of mechanical waves? check all that apply ⭕️ particles of the medium move back and fourth, but do not move with the wave. ⭕️ the particles of the medium always move parallel to the wave motion. ⭕️ wave motion begins with a disturbance in the medium. ⭕️ waves transport energy from a source outward, away from the source.

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)