The problem statement, all variables and given/known data[/b](adsbygoogle = window.adsbygoogle || []).push({});

A sledgehammer with a mass of 2.30 kg is connected to a frictionless pivot at the tip of its handle. The distance from the pivot to the center of mass is r_cm=0.570 m, and the moment of inertia about the center of mass is I_cm = 0.0390 kgm2. If the hammer is released from rest at an angle of theta=40.0 degrees such that H=0.366 m, what is the speed of the center of mass when it passes through horizontal?

The diagram is attached.

3. The attempt at a solution

My prof did a similar question during class with energy, and so that's the way I tried to solve it. With this incorrect, I honestly don't know how else to go about this problem.

E1 = E2

mgH = (1/2)Iw^2

2mgH/I = w^2

w = √(2mgH/I)

w = 20.568 rad/s

*Because the question asks for speed, I tried this as the answer and the units were rejected. So I tried to solve for velocity instead.

mgH = (1/2)I(v^2/r^2)

v^2 = 2mgHr^2/I

v = √(2mgHr^2/I)

v = 19.37 m/s

Again, incorrect.

Does anyone know how to help? I would genuinely appreciate it. I've got a final coming up and not knowing how to go about this problem, or even what specifically to solve for when asked for 'speed', is really making me panic.

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# Homework Help: Pivoting Sledgehammer

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