Answer:

Explanation:
For sound waves we have v=d/t where v is the speed of sound and d the distance between the astronauts, while for electromagnetic waves we have c=D/t where c is the speed of light and D the distance between the spaceship and Earth. <em>We have written both times as the same</em> because is what is imposed by the problem, so we have t=d/v=D/c, which means:

And for our values:

Answer:
Temperature decreases because the number of collision of the molecules decreases as they escape or evaporate. Molecules are in constant motion. Increase in temperature leads to increase in average kinetic energy of the molecules.
Answer:
A and c, hope i helped xx
Explanation:
Explanation:
It is given that,
Mass of the truck, m = 2000 kg
Initial velocity of the truck, u = 34 km/h = 9.44 m/s
Final velocity of the truck, v = 58 km/h = 16.11 m/s
(a) Change in truck's kinetic energy, 



(b) Change in momentum of the truck, 


Hence, this is the required solution.
Answer: The average velocity is -0.965m/s
Explanation: The first step is to calculate the two velocities is both directions. A velocity is a distance per unit time.
V=d/ t
=-5.7/2.1
=-2.7m/s
For the other direction the velocity is
V=7.3/9.5
=0.77m/s
The average velocity the add the velocities and divide them by 2.
V=-2.7+0.77/2
V= 0.965m/s