Back to School
I'll admit that I was initially duped on this one, but I blame the fact that the video was misleading. Still an interesting demonstration of some fundamental physics principles.
2019 Stats - Solar
The downward trend continues, though it is not more than expected. And if I scale the chart from zero, the trend doesn't look nearly so precipitous. Also, I found a website where I can upload my solar data and it will add weather info. 2019 is the first year I've had this active, but I'm excited to be able to see how much the number of sunny days factors into my solar performance. Being above or below my average for a particular month was strongly correlated with the prevalence of sunny days. Overall, 78% of days were "fine" in Fernley Nevada in 2019.
Comments
So, how do you explain the fact that the second block seems to having more energy?
The trick is that you can't use conservation of mechanical (kinetic and potential) energy with inelastic collisions since there is always heat (aka thermal energy) created in the process. The bullet in the non-rotating block will have penetrated deeper into the wood and thus created more heat (this is not only evident from its lesser energy but also from considering that the spinning block would start moving away from the bullet sooner than the non-spinning block).
The simplest way to think about the situation is in terms of momentum. Linear momentum is always conserved, so the fact that the bullets had nearly identical momenta before the collision tells you that the blocks will have identical vertical momenta and thus reach the same height.
Let's see. If we imagine firing bouncy balls at the blocks of wood, we now have to consider what happens to the rebounding ball as well. It's safe to assume that the ball shot at the middle of the block would rebound back with a greater velocity than the other one (since the other block gives more as it starts to rotate).
From an energy perspective, the ball rebounding off the middle of the block keeps a greater portion of its initial energy, so the off center block gets more energy from the collision. But it's splitting that energy between potential and rotational. So energy doesn't give us a definitive answer.
Momentum is our friend once again. It tells us that the block hit in the middle will go higher because the ball with the larger velocity in the opposite direction had a greater change in momentum and thus gave the block more upward momentum.
Nice physics intuition Ryan.