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notsponge [240]
3 years ago
5

A 70-kg pole vaulter running at 11 m/s vaults over the bar. Her speed when she is above the bar is 1.3 m/s. Neglect air resistan

ce, as well as any energy absorbed by the pole, and determine her altitude as she crosses the bar.
Physics
1 answer:
yKpoI14uk [10]3 years ago
5 0

Answer:

h_{B} = 6.083\,m

Explanation:

Let assume that pole vaulter begins running at a height of zero. The pole vaulter is modelled after the Principle of Energy Conservation:

K_{A} = K_{B} + U_{g,B}

\frac{1}{2}\cdot m \cdot v_{A}^{2} = \frac{1}{2}\cdot m \cdot v_{B}^{2} + m\cdot g \cdot h_{B}

The expression is simplified and final height is cleared within the equation:

\frac{1}{2}\cdot (v_{A}^{2} - v_{B}^{2}) = g\cdot h_{B}

h_{B} = \frac{(v_{A}^{2}-v_{B}^{2})}{2\cdot g}

h_{B} = \frac{[(11\,\frac{m}{s} )^{2}-(1.3\,\frac{m}{s} )^{2}]}{2\cdot (9.807\,\frac{m}{s^{2}} )}

h_{B} = 6.083\,m

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