Answer:
4.35×10⁻⁴ m
Explanation:
(a)
From wave,
v = λf...................... Equation 1
Where v = speed of sound in air, λ = wavelength of sound, f = frequency of sound.
Make λ the subject of formula in equation 1
λ = v/f................. Equation 2
Given: v = 343, f = 3.45 MHz = 3.45×10⁶ Hz
Substitute into equation 2
λ = 343/(3.45×10⁶)
λ = 99.42×10⁻⁶ m
λ = 9.942×10⁻⁵ m
(b)
using,
v' = λ'f............... Equation 3
Where v' = speed of sound in tissue, λ' = wavelength of sound in tissue.
make λ' the subject of the equation
λ' = v'/f......................Equation 4
Given: v' = 1500 m/s, f = 3.45 MHz = 3.45×10⁶ Hz
Substitute into equation 4
λ' = 1500/(3.45×10⁶)
λ' = 434.783×10⁻⁶
λ' ≈ 4.35×10⁻⁴ m.
I believe its the third answer
The Answer Second one , Plasma
Answer: h = 0.30 m
Explanation:
A person jumping from height h would possess potential energy = m g h
which will convert completely into kinetic energy as person hits the ground. Now, the maximum energy absorbed by the person can be = 200 J
m = 67 kg
g = 9.8 m/s²
⇒ m g h = 200 J
⇒ h = 200 J / (67 kg × 9.8 m/s²) = 0.30 m
Hence, a person can land safely on both legs without breaking them from a height of 0.30 m only.
