Impulse and Momentum!!!

Physics appeared to me this weekend while playing tennis. I was playing a match when suddenly realized that this was all related to what I was just learning in physics class. It all had to do with impulse and momentum. While hitting the ball, the momentum remained unchanged throughout the system. My racket and the ball retained their same momentums before and after the collision. This is just like an inelastic, “bouncy” collision. Both the ball and my racket have initial velocities and final velocities; therefore, the momentum remains the same (conservation of momentum). Through this collision, the momentum remains the same however; the KE is changed because it is an inelastic collision where, KE is lost through factors such as, heat (of the collision), friction, air resistance, etc… I found tennis is related to many physics concepts, impulse momentum being two major ones. Physics just never ceases to “POP!” out at me.

WORK AND ENERGY

This weekend, while working out in the weight room, Physics suddenly appeared to me!!! I found myself on the bench press when, Mr. Kohara popped into my head. I was reminded of what we discussed in class about work and energy. He pretty much said that no work was being done when an object is held motionless in the same position because its kinetic and potential energies remain unchanged. So there I was laying on the bench, puzzled. I could not figure out how no work was being done as I held the barbell over my chest, with arms fully extended and practically motionless. It felt like I was doing a ton of work as time went on however; I remembered that I was NOT! As explained to the relationship between work and energy, no work was being done because the total energy (DeltaKE+DeltaPE) which is equivalent to the amount of work (W) was unchanged (0), thus for meaning the amount of work was (0) as well. Physics once again Popped Out and surprised me in an unsuspecting time!