Answer:
Les changements d'état sont des changements physiques. Ils se produisent lorsque la matière absorbe ou perd de l'énergie. Les processus dans lesquels la matière change entre les états liquide et solide sont la congélation et la fusion. Les processus dans lesquels la matière change entre les états liquide et gazeux sont la vaporisation, l'évaporation et la condensation.
Im not french and I used translate so if it messes up with the translation, I am sorry
Answer:
Explanation:
Initially no of atoms of A = N₀(A)
Initially no of atoms of B = N₀(B)
5 X N₀(A) = N₀(B)
N = N₀ 
N is no of atoms after time t , λ is decay constant and t is time .
For A
N(A) = N(A)₀ 
For B
N(B) = N(B)₀ 
N(A) = N(B) , for t = 2 h
N(A)₀ = N(B)₀
N(A)₀ = 5 x N₀(A)
= 5
= 5 
half life = .693 / λ
For A
.77 = .693 / λ₁
λ₁ = .9 h⁻¹
= 5
Putting t = 2 h , λ₁ = .9 h⁻¹
= 5 
= 30.25
2 x λ₂ = 3.41
λ₂ = 1.7047
Half life of B = .693 / 1.7047
= .4065 hours .
= .41 hours .
Answer:
Spring constant = YA / L
Explanation:
Let F be the force being applied on cross sectional area A of metal bar due to which an extension of ΔL is obtained in the wire of length L then
stress = F / A
strain = ΔL /L
Young's modulus = ( F / A ) / (ΔL /L)
Y = ( F L / A ΔL )
( F / ΔL ) = ( YA / L )
Spring constant = ( F / ΔL )
Spring constant = YA / L
Wave speed = fλ
=(5 x 10^14)(4 x 10^-7)
=2 x 10^8
Where f is the frequency and λ is the wavelength
