Answer
given,
mass of car (m) = 1200 Kg
speed of cur, u = 25 m/s
mass of truck(M) = 9000 Kg
speed of truck, u' = 20 m/s
v = 18 m/s
a) using conservation of momentum
m u + M u' = m v + M v'
1200 x 25 + 9000 x 20 = 1200 x 18 + 9000 x v'
9000 v' = 188400
v' = 20.93 m/s
b) To calculate losses, we will find the kinetic energies before & after collision. Any difference would give us the losses (in energy form).
(K E)₁= (K E)₂+ Losses
losses = (K E)₂ - (K E)₁
=
=
=9038 J
Answer:
the mass of steam at 100°C must be mixed is 150 g
Explanation:
given information:
ice's mass, = 490 g = 0.49 kg
steam temperature, T = 100°C
liquid water temperature, T = 89.0°C
specific heat of water, = 4186 J/kg.K = 4.186 kJ/kg.K
latent heat of fusion, = 333 kJ/kg
latent heat of vaporization, = 2256 kJ/kg
first, we calculate the heat of melted ice to water
Q₁ =
where
Q = heat
= mass of the ice
= latent heat of fusion
thus,
Q₁ =
= 0.49 x 333
= 163.17 kJ
then, the heat needed to increase the temperature of water to 89.0°C
Q₂ =
(89 - 0), the temperature of ice is 0°C
= specific heat of water
so,
Q₂ =
(89 - 0)
= 0.49 x 4.186 x 89
= 182.55 kJ
so, the heat absorbed by the ice is
Q = Q₁ + Q₂
= 163.17 + 182.55
= 345.72 kJ
the temperature of the steam is 100°C, so the mass of the steam is
Q = +
(100 - 89)
Q = (
+
(11))
= Q/ [
+
(11)]
= 345.72/ [2256 + (4.186 x 11)]
= 0.15 kg
= 150 g
Answer:
β = 114 db
Explanation:
The intensity of sound in decibles is
β = 10 log
in most cases Io is the hearing threshold 1 10-12 W / cm²
let's calculate the intensity of each instrument
I / I₀ = 10 (β / 10)
I = I₀ 10 (β / 10)
trumpet
I1 = 1 10⁻¹² 10 (94/10)
I1 = 2.51 10⁻³ / cm²
Thrombus
I2 = 1 10⁻¹² 10 (107/10)
I2 = 5.01 10-2 W / cm²
low
I3 =1 1-12 (113/10) W/cm²
I3 = 1,995 10-1 W / cm²
when we place the three instruments together their sounds reinforce
I_total = I₁ + I₂ + I₃
I_ttoal = 2.51 10-3 + 5.01 10-2 + 1.995 10-1
I_total = 0.00251 + 0.0501 + 0.1995
I_total = 0.25211 W / cm²
let's bring this amount to the SI system
β = 10 log (0.25211 / 1 10⁻¹²)
β = 114 db