Let say the two train cars are of masses 
and 
now if the speed of two cars are 
and 
then we can say that the momentum of two cars before they collide is given by
here two cars are moving in opposite direction so we can say that the net momentum is subtraction of two cars momentum.
Now since in these two car motion there is no external force on them while they collide
So the momentum of two cars are always conserved.
hence we can say that the final momentum of two cars will be same after collision as it is before collision
Answer:
Number of turns in secondary will be 7
Explanation:
We have given primary voltage 
Number of turns in the primary is 
Secondary voltage is given 
We have to find the number of turns in secondary
We know that 
So 
As the number of turns can not be in decimal so number of turns will be 7
Explanation:
F = ma, and a = Δv / Δt.
F = m Δv / Δt
Given: m = 60 kg and Δv = -30 m/s.
a) Δt = 5.0 s
F = (60 kg) (-30 m/s) / (5.0 s)
F = -360 N
b) Δt = 0.50 s
F = (60 kg) (-30 m/s) / (0.50 s)
F = -3600 N
c) Δt = 0.05 s
F = (60 kg) (-30 m/s) / (0.05 s)
F = -36000 N
None of the above
mass is measurement of how much stuff in inside something.
if you freeze or heat an object, you merely change the state of the object. the mass is conserved.
if you change the elevation, nothing happens to the mass. the stuff will not leave the object.
so it is None of the above
