Answer
B. X
A plate of glass or metal ruled with very close parallel lines, producing a spectrum by diffraction and interference of light.
diffraction grating is an optical component that splits and diffracts light into several beams travelling in different directions. The light emerges with its colours separated.
The gravitational constant (G) in its base SI units is
3/2
m
3
k
g
/
s
2
But is often seen written as
⋅
N
⋅
2/2
m
2
/
k
g
2
Where N is the Newton unit. N=kg ⋅
⋅
m/s 2
2
Answer:
elastic potential energy
You input potential (stored) energy into the rubber band system when you stretched the rubber band back. Because it is an elastic system, this kind of potential energy is specifically called elastic potential energy.
Explanation:
Let the mass of 2500 kg car be 
and it's velocity be 
and the mass of 1500 kg car be 
and it's velocity be 
.
After the bumping the mass be M and it's velocity be V.
By law of conservation of momentum we have
2500 * 5 + 1500 * 1=4000 * V
V = 14000/4000 = 7/2 = 3.5 m/s
So the velocity of the two-car train = 3.5 m/s
