Physics
1st Edition
ISBN: 9780133256925
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Page 959: Practice Problems
Exercise 20
Solution 1
Solution 2
Step 1
1 of 2
$textbf{Given:}$
$E_o = 18000$ kWh
$textbf{Find:}$ mass
Using the mass-energy equivalence formula, we can find the mass, $m$ as follows:
$$
begin{align*}
E_o &= mc^2 \
m &= dfrac{E_o}{c^2} \
&= dfrac{(18000 text{ J/s})(1000)(3600 text{ s})}{(3.0 times 10^8 text{m/s})^2} \
&= 7.2 times 10^{-7} text{ kg}
end{align*}
$$
Hence, the mass required to have a rest energy of 18000 kWh is $boxed{7.2 times 10^{-7} text{ kg}}$
Result
2 of 2
m = $7.2 times 10^{-7} text{ kg}$
Step 1
1 of 2
Here we have to use the mass-energy equivalence i.e. to equate
$$
18000text{ kWh} = mc^2,
$$
and this gives
$$
m= frac{18000times 1000times 3600 text{ J}}{9times 10^{16}text{(m/s)}^2} = 7.2times 10^{-7}text{ kg}.
$$
Result
2 of 2
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