LEARNING OBJECTIVES:

I will work with my team to solve increasingly complex energy problems during today's class

WORDS O' THE DAY:

• Work (Force through displacement, usually measured in Nm)
• Energy (measured in Joules)
• Power (measured in Joules/sec = Watts)

FORMULAE OBJECTUS:

Work = ∆E = Fd = Fdcosθ

KE = 1/2mv²

Power = P = energy/time

∆E = +/- W

WORK O' THE DAY:

You're lying flat on your back on a warm spring day in a lovely meadow. Of *course* you have your wrist rocket slingshot! However this time instead of frozen grapes you have a pouch full of 3/8 in diameter steel ball bearings (mass = 0.00355 kg)

You launch a ball bearing upwards at a hefty 73.25 m/s.

Use energy concerns to determine the h_max for that ball bearing? (Hint: I haven't told you a critical aspect of the problem. Without knowing that you cannot continue-- please discuss)

1) Now that you have discussed that and I've provided you with the correct additional info, please determine how high that grape goes:

• Sketch the situation showing all initial conditions either explicitly stated or implied.
• Write the appropriate Energy equation.

2) Without doing ANY calculations whatsoever, please turn to someone in your group and tell them the fastest velocity the grape achieves on the way back down to the ground.

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1a (revised)

You're lying flat on your back in a meadow blah blah blah (same as before). You forget to measure how fast your ball bearing is going when you launch it but you quickly realize that's fine as long as you accurately measure how high it goes.

You quickly do that (we won't worry about just how you do that) and you determine the ball bearing has reached a height of 246.123 meters.

1. Sketch the situation showing all initial conditions either explicitly stated or implied.
2. Write the appropriate Energy equation.
3. Determine how fast you launched the ball bearing if, once again, we ignore friction

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Your second cousin (once removed) is visiting from MIT where they are studying orbital mechanics. They tell you that your ball bearing is likely to lose 1.254 J of energy due to friction on the way up to hmax.

With that in mind:

1. Sketch the situation showing all initial conditions either explicitly stated or implied.
2. Write the appropriate Energy equation.
3. Determine how how high the ball bearing goes
4. Determine how fast the ball bearing is going when it hits the ground

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Now that we know that the ball bearing will go 208 m (210 m works too, sig figs), work with your team to QUICKLY determine how fast the ball bearing is going when it hits the ground.

MAKE SURE to talk about it first, there is a bugaboo here that has an elegant & pretty easy solution.

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Work with your team to craft an EASY, MODERATE & TOUGH work/energy problem. Be sure and use chatGPT to verify your math. If chatGPT is wrong (it sometimes is, make sure you have the math to prove it!)