<u>Answer:</u>
The final velocity of the two railroad cars is 1.09 m/s
<u>Explanation:</u>
Since we are given that the two cars lock together it shows that the collision is inelastic in nature. The final velocity due to inelastic collision is given by

where
V= Final velocity
M1= mass of the first object in kgs = 12000
M2= mas of the second object in kgs = 10000
V1= initial velocity of the first object in m/s = 2m/s
V2= initial velocity of the second object in m/s = 0 (given at rest)
Substituting the given values in the formula we get
V = 2×12000 + 0x100012000 + 10000= 2400022000= 1.09 m/s

Which is the final velocity of the two railroad cars
Has an Environmental Impact. Perhaps the largest disadvantage of hydroelectric energy is the impact it can have on the environment.
It Displaces People.
It's Expensive.
There are Limited Reservoirs.
There are Droughts.
It's Not Always Safe
Answer:
300 Nm ; 300 J
Explanation:
Given that:
Force (F) = 20 N
Distance (d) = 15 m
The kinetic energy (Workdone) = Force * Distance
Kinetic Energy = 20N * 15m
Kinetic Energy = 300Nm
K. E = 1/2
The period of the wave is the reciprocal of its frequency.
1 / (5 per second) = 0.2 second .
The wavelength is irrelevant to the period. But since you
gave it to us, we can also calculate the speed of the wave.
Wave speed = (frequency) x (wavelength)
= (5 per second) x (1cm) = 5 cm per second