Explanation:
It is given that,
Frequency of diagnostic ultrasound, f = 3.82 MHz = 3820 Hz
The speed of the sound in air, v = 343 m/s
(a) We need to find the wavelength in air of such a sound wave. Let it is given by λ₁
i.e.
(b) If the speed of sound in tissue is 1650 m/s .
Hence, this is the required solution.
Answer:
ΔT = 59.9 ° C
Explanation:
For this exercise the brake energy is totally converted into heat
Let's calculate the vehicle energy
K = ½ m v²
Let's reduce the units to the SI system
v = 30 mph (1609.34 m / mile) (1h / 3600s) = 13.41 m / s
Em = K = ½ 1200 13.41²
K = 1.079 105 J
All this energy is transformed into heat
Em = Q
The expression for heat is
Q = m ΔT
ΔT = Q / m
The specific heat of iron is = 450 J / Kg ºC
ΔT = 1,079 105 / (4.0 450)
ΔT = 59.9 ° C