Answer: 19 s
Explanation:
The relationship between speed, distance and time is given by:
velocity= distance/time
time= distance/velocity= 323 m/17 m/s= 19 s
Answer: v = 
Explanation: q = magnitude of electronic charge = 
mass of an electronic charge =
V= potential difference = 4V
v = velocity of electron
by using the work- energy theorem which states that the kinetic energy of the the electron must equal the work done use in accelerating the electron.
kinetic energy =
, potential energy = qV
hence, 

Cosmic background radiation is electromagnetic radiation from the sky with no discernible source. The origin of this radiation depends on the region of the spectrum that is observed.
Here we have perfectly inelastic collision. Perfectly inelastic collision is type of collision during which two objects collide, stay connected and momentum is conserved. Formula used for conservation of momentum is:

In case of perfectly inelastic collision v'1 and v'2 are same.
We are given information:
m₁=0.5kg
m₂=0.8kg
v₁=3m/s
v₂=2m/s
v'₁=v'₂=x
0.5*3 + 0.8*2 = 0.5*x + 0.8*x
1.5 + 1.6 = 1.3x
3.1 = 1.3x
x = 2.4 m/s