Answer:
a. d₁/d₂ = 1.09 b. 0.054 mW
Explanation:
a. What is the ratio of the diameter of the first student's eardrum to that of the second student?
We know since the power is the same for both students, intensity I ∝ I/A where A = surface area of ear drum. If we assume it to be circular, A = πd²/4 where r = radius. So, A ∝ d²
So, I ∝ I/d²
I₁/I₂ = d₂²/d₁² where I₁ = intensity at eardrum of first student, d₁ = diameter of first student's eardrum, I₂ = intensity at eardrum of second student, d₂ = diameter of second student's eardrum.
Given that I₂ = 1.18I₁
I₂/I₁ = 1.18
Since I₁/I₂ = d₂²/d₁²
√(I₁/I₂) = d₂/d₁
d₁/d₂ = √(I₂/I₁)
d₁/d₂ = √1.18
d₁/d₂ = 1.09
So, the ratio of the diameter of the first student's eardrum to that of the second student is 1.09
b. If the diameter of the second student's eardrum is 1.01 cm. how much acoustic power, in microwatts, is striking each of his (and the other student's) eardrums?
We know intensity, I = P/A where P = acoustic power and A = area = πd²/4
Now, P = IA
= I₂A₂
= I₂πd₂²/4
= 1.18I₁πd₂²/4
Given that I₁ = 0.58 W/m² and d₂ = 1.01 cm = 1.01 × 10⁻² m
So, P = 1.18I₁πd₂²/4
= 1.18 × 0.58 W/m² × π × (1.01 × 10⁻² m)²/4
= 0.691244π × 10⁻⁴ W/4 =
2.172 × 10⁻⁴ W/4
= 0.543 × 10⁻⁴ W
= 0.0543 × 10⁻³ W
= 0.0543 mW
≅ 0.054 mW
Newton is the SI unit of force . Newton is the name of a British scientist and the name of unit is to honour him. The unit is actually Kg.m/s 2 The unit can be derived by the formula. Take the example of weight. It's formula is W = mg . We know that the unit of mass is kg and gravity is m/s 2 so the unit of weight becomes kg.m/s 2 This unit is known as a Newton. It is always given a capital letter because it is someone's name. Other units that are always capitalised (upper case) are Ampere (Amp), Watt, Volt, Coulomb, Kelvin, Celsius, Fahrenheit, Curie, Roentgen because they are also people's names.
Answer:
The rate at which the pump moves oil is 1 m³/s
Explanation:
Assumptions:
- there is steady-state flow
- oil and water are incompressible
- first fluid is water, second fluid is oil and third fluid is the mixture of oil and water.
where;
ρ is the fluid density
Q is the volumetric flow rate
Substitute in Q₃ in equation i
divide through by ρ₁
Make Q₂ the subject of the formula
Therefore, the rate at which the pump moves oil is 1 m³/s
Answer:
<u>Average Velocity:</u>
When a body covers some displacement moving from point A to B, in a given time,t. Then dividing the total distance covered by the time taken to complete the displacement is called as the average velocity of that car.
We can calculate the average velocity of car by subtracting the initial displacement of a body,s₁ from the final displacement position of the body, s₂. And then dividing by the initial time,t₁ been subtracted from the final time,t₂.
We will get the required results, now if we want to obtain the results in the final three seconds then, we can have the following explanation to that as given.
Explanation:
Lets say, that we have the car moving for 10 seconds and then it stops at the eleventh second of the trip on final position, of the displacement. Then we divide the whole trips into small segments, as we will have the different velocity at each interval but, the velocity is unknown at the last 3 seconds is unknown=?.
- Total time taken, Δt= 11 seconds,
- Then lets say the velocity at the 8th second is , v=25 m/s,then
- Δv=x₂-(25)/11-0,⇒Δv=x₂-25/11,
Answer:
Density = mass/volume
Volume of cube = mass/density
630g/8.94 = 70.5cm^3 (3s.f.)
Since it is a cube, its dimensions of Length x breadth x height=volume
Take 70.5 amd cube root it
![\sqrt[3]{70.4697986577)](https://tex.z-dn.net/?f=%20%5Csqrt%5B3%5D%7B70.4697986577%29)
=4.13 (3s.f)
hence , it would be 4.13 x 4.13 x 4.13 to find the volume
Hence, the answer would be 4.13cm(3s.f.)
