Assume that Mars and Earth are in the same plane and that their orbits around the Sun are circles (Mars is ≈230×10^6km from the Sun and Earth is ≈150×10^6km from the Sun). a) How long would it take a message sent as radio waves from Earth to reach Mars when Mars is nearest Earth?

b) How long would it take a message sent as radio waves from Earth to reach Mars when Mars is farthest from Earth?

Explanation:

speed of light ≈ 300 000 000 m/s

a) How long would it take a message sent as radio waves from Earth to reach Mars when Mars is nearest Earth?

(230e9 - 150e9) / 3e8 = 277 s or 4 minutes 27 seconds.

b) How long would it take a message sent as radio waves from Earth to reach Mars when Mars is farthest from Earth?

(230e9 + 150e9) / 3e8 = 1267 s or 21 minutes 6 seconds.

d) the number of neutrons plus the number of protons

answer: 802.3 kilo joules of energy represents 191.75 kilo calorie of energy.

explanation:

energy released during combustion of one mole methane = 802.3 kilo joules

if 1 kilo joule = 0.239006   kilo calorie

then ,802.3 kilo joule will be = 802.30.239006 kilo calorie

802.3 kilo joule = 191.75 kilo calorie

hence, the energy in kilo calorie is 191.75 kilo calorie.