Question #64d01

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Answer 1 · 2017-10-15T00:54:21

72.74 m/s

Total energy of glass at that height = Potential energy

$= m g h$ $= mgh$

$= 270 m g$ $= 270mg$

Total energy of glass when it reaches the ground = Kinetic energy

= $\frac{m v^{2}}{2}$ $(mv^2)/2$

Initial Total energy = Final Total energy

$270 m g = \frac{m v^{2}}{2}$ $270 mg = (mv^2)/2$

$540 m g = m v^{2}$ $540mg = mv^2$

Divide both sides by “m”

$540 g = v^{2}$ $540g = v^2$

$v = \sqrt{540 g}$ $v = sqrt(540 g)$

$v = \sqrt{540 \times 9.8}$ $v = sqrt(540 × 9.8)$

$v = 72.74 m s^{- 1}$ $v = 72.74 ms^-1$