Answer:
The density of one halves 11.3 g / cm cube
Explanation:
Density remain same because cutting the bar in half , mass and volume will decrease to half so density will not change .
density =
Answer:
The BOD concentration 50 km downstream when the velocity of the river is 15 km/day is 63.5 mg/L
Explanation:
Let the initial concentration of the BOD = C₀
Concentration of BOD at any time or point = C
dC/dt = - KC
∫ dC/C = -k ∫ dt
Integrating the left hand side from C₀ to C and the right hand side from 0 to t
In (C/C₀) = -kt + b (b = constant of integration)
At t = 0, C = C₀
In 1 = 0 + b
b = 0
In (C/C₀) = - kt
(C/C₀) = e⁻ᵏᵗ
C = C₀ e⁻ᵏᵗ
C₀ = 75 mg/L
k = 0.05 /day
C = 75 e⁻⁰•⁰⁵ᵗ
So, we need the BOD concentration 50 km downstream when the velocity of the river is 15 km/day
We calculate how many days it takes the river to reach 50 km downstream
Velocity = (displacement/time)
15 = 50/t
t = 50/15 = 3.3333 days
So, we need the C that corresponds to t = 3.3333 days
C = 75 e⁻⁰•⁰⁵ᵗ
0.05 t = 0.05 × 3.333 = 0.167
C = 75 e⁻⁰•¹⁶⁷
C = 63.5 mg/L
Answer:
I believe the answer is speed up.
Explanation:
this is because when water heats up the molecules move father apart from each other they speed up, eventually causing the water to boll
Answer:
the required electrical power when the room air and surroundings are at 30°C.= 52.51822 Watt
Explanation:
Power required to maintain the surface temperature at 150°C from 20°C
P= εσA(T^4-t^4)
P= power in watt
ε= emissivity
A= area of surface
T= 150°C= 423 K
t= 20°C= 303K
/sigma= 5.67×10^{-8} watt/m^2K^4
putting vales we get

P=52.51822 Watt
the required electrical power when the room air and surroundings are at 30°C.= 52.51822 Watt
Answer:
The speed of the vehicles immediately after the collision is 5.84 m/s.
Explanation:
The speed of the vehicles after the collision can be found by conservation of linear momentum:


Where:
m₁: is the mass of the car = 0.5 ton = 500 kg
m₂: is the mass of the lorry = 9.5 ton = 9500 kg
: is the initial speed of the car = 40 km/h = 11.11 m/s
: is the initial speed of the lorry = 20 km/h = 5.56 m/s
: is the final speed of the car =?
: is the final speed of the lorry =?
Since the two vehicles become tightly locked together after the collision
=
:


Therefore, the speed of the vehicles immediately after the collision is 5.84 m/s.
I hope it helps you!