In order to compute the final velocity of the trains, we may apply the principle of conservation of momentum which is:
initial momentum = final momentum
m₁v₁ = m₂v₂
The final mass of the trains will be:
10,000 + 10,000 = 20,000 kg
Substituting the values into the equation:
10,000 * 3 = 20,000 * v
v = 1.5 m/s
The final velocity of the trains will be 1.5 m/s
Answer: 
Explanation:
We have the following equation:
We have to find 
this means we have to isolate it:
Answer:
mass of block=2.7 gm
Explanation:
concept: Density=mass/volume
given:ρ=2700 kg/m^3 and v=250 cm^3 (in cm^3 not in m^3)
=> v= convert cm^3 to m^3
there fore= 1 cm^3=1 cm*1 cm*1 cm
i.e 1 cm^3=1/100*1/00*1/100 m^3 => 1 cm^3=1/1000000 m^3
ρ=m/v
=>mass=ρ*volume
=>mass=2700*1/10^-6
=>mass=2.7*10^-3 kg =>2.7 gm
