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Standard IX

Physics

Second Law of Motion

From what hei...

Question

From what height must a hailstone at $0^{o}$ C fall in order that it may melt on reaching the ground assuming that $7 %$ energy is lost during fall

36.87 k m

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23.4 k m

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15.9 k m

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None of these

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Solution

The correct option is A $36.87 k m$
$h = m g h$

$= \frac{7}{100} m g h$

Energy spent in melting-

$= m g h - \frac{7}{100} m g h$

$= \frac{93}{100} \frac{m g h}{J}$

$h = \frac{100 \times 4.2 \times 10^{7} \times 80}{93 \times 980} c m = 36.9 k m$

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From what height must a hailstone at 0o C fall in order that it may melt on reaching the ground assuming that 7% energy is lost during fall

The correct option is A 36.87kmh=mgh =7100mgh Energy spent in melting- =mgh−7100mgh =93100mghJ h=100×4.2×107×8093×980cm=36.9km

From what height must a hailstone at $0^{o}$ C fall in order that it may melt on reaching the ground assuming that $7 %$ energy is lost during fall

The correct option is A $36.87 k m$
$h = m g h$

$= \frac{7}{100} m g h$

Energy spent in melting-

$= m g h - \frac{7}{100} m g h$

$= \frac{93}{100} \frac{m g h}{J}$

$h = \frac{100 \times 4.2 \times 10^{7} \times 80}{93 \times 980} c m = 36.9 k m$