How long does it take a message to travel from earth to a spacecraft at mars at its farthest from earth (about 400 million km)? express your answer to three significant figures and include the appropriate units. t =?

A message needs to be traveled to mars from earth. Distance between Earth and Mars (given) s = 400 million km
 Speed of light = 3.00—10^5 km/ sec
 We know Velocity = distance / time => time = distance / velocity
 Time taken t = 400 million km / 3.00—10^5 = 400 x 10^6 / 3 x 10^5 = 1333.3 sec Time taken t = 22 min

12m/s

Explanation:

x = (21 + 22t – 6 t2) m,

We can express change bin velocity as

dx/dt= -12t + 22

But Velocity is changing

interval t = 1 s

t = 4 s

at t = 1, x = 21 + 22(1) -6(1)^2

=37

at t = 4, x = 21 + 22(4) -6(4)^2

=13

Distance travelled at interval t = 1 s

t = 4 s

X2 - X1=13- 37. = - 24m

Velocity= displacement/ time

= 24/(3-1)=12 m/s