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**[SOLVED] Pendulum Momentum Question**

**1. Homework Statement**

Figure 8-34 shows a pendulum of length L = 1.25 m. Its bob has speed v0 when the cord makes an angle theta0 = 40 degrees with the vertical.

What is the speed of the bob when it is in its lowest position if v0 = 8 m/s?

The speed is 8.35 m/s.

What is the least value that v0 can have if the pendulum is to swing down and then up to a horizontal position?

**2. Homework Equations**

W + KE1 + PE1 = KE2 + PE2

**3. The Attempt at a Solution**

W + KE1 + PE1 = KE2 + PE2:

0 + (1/2)m(8.57 m/s)^2 + 0 = (1/2)m v^2 + m(9.8 m/s^2)1.25m

v= 6 or 7 something. The answer in the book is 4.33 m/s

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