Length of the pendulum, l= 1.5 m

Potential of the bob at the horizontal position = mgh = mgl

The initial energy dissipated against air resistance when the bob moves from the horizontal position to the lowermost point= 5%

The total kinetic energy of the bob at the lowermost position = 95% of the total potential energy at the horizontal position

(\( \dfrac{1}{2}\))mv^{2} = (\( \dfrac{95}{100}\)) mgl

v^{2} =2 [(\( \dfrac{95}{100}\)) x 9.8 x 1.5]

v^{2} =2 ( 13.965) = 27.93

v = \( \sqrt{27.93}\) = 5.28 m/s

Answered by Pragya Singh | 1 year agoA person trying to lose weight (dieter) lifts a 10 kg mass, one thousand times, to a height of 0.5 m each time. Assume that the potential energy lost each time she lowers the mass is dissipated.

**(a)** How much work does she do against the gravitational force?

**(b)** Fat supplies 3.8 × 10^{7}J of energy per kilogram which is converted to mechanical energy with a 20% efficiency rate. How much fat will the dieter use up?

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