(a) The distance to a star is approximately 8.64 ✕ 1018 m. If this star were to burn out today, in how many years would we see it disappear? years (b) How long does it take sunlight to reach Earth? minutes (c) How long does it take for a microwave radar signal to travel from Earth to the Moon and back? (The distance from Earth to the Moon is 3.84 ✕ 105 km.) s

A. 922 yrs

B. 8.21mins

C. 2.56 seconds

Explanation:

Pls refer to attached file

(a)  913.874 Years.

(b) 8 minutes.

(c) 2.56177 Seconds.

Explanation:

(a) Following Equation relates Distance to Velocity and time.

(S is for Distance,

in it we have.

S = , V = 299792458m/s (Velocity of Light).

t = ?

Rearranging and solving for time gives us. t =

which when converted to years , we have t = 913.874years, that is how long it will take for us to notice that the star has been burned out.

(b) it take 8 minutes for sun light to reach earth, how.? because distance from earth to sun is 150.46 million Km. doing same calculations as in (a) gives us 8 minutes.

(c) Distance to moon and back is twice as much, because obviously it is round trip, so S = 2 x 3.84x10^5Km.

using same logic as in (a) and (b) we get t = 2.56177 seconds. that is how long light takes to reach moon and come back.

energy stored in the capacitor= 9.72 x 10⁻⁴ j

explanation:

the energy stored in the capacitor is given by

e= 1/2 c v²

e= energy stored

c= capacitance= 1.5 µc= 1.5 x 10⁻⁶f

v= potential difference=36 v

so energy stored= e= 1/2 (1.5 x 10⁻⁶) (36)²

energy stored= 9.72 x 10⁻⁴j