Answer:
As the liquid cools down, the amount of potential energy is reduced and the molecules start to move slower. When the water temperature reaches around 0°C, the molecules stick together and form a solid – ice
The "stuff" (molecules) in water is more tightly packed than in ice, so water has greater density than ice. Don't let the fact that ice is a solid fool you! As water freezes it expands. So, ice has more volume (it takes up more space, but has less density) than water
Explanation:
Who knows, not me, not me and not me again
Answer:
The mass of the block, M =T/(3a +g) Kg
Explanation:
Given,
The upward acceleration of the block a = 3a
The constant force acting on the block, F₀ = Ma = 3Ma
The mass of the block, M = ?
In an Atwood's machine, the upward force of the block is given by the relation
Ma = T - Mg
M x 3a = T - Ma
3Ma + Mg = T
M = T/(3a +g) Kg
Where 'T' is the tension of the string.
Hence, the mass of the block in Atwood's machine is, M = T/(3a +g) Kg
Answer:
How to find the maximum height of a projectile?
if α = 90°, then the formula simplifies to: hmax = h + V₀² / (2 * g) and the time of flight is the longest. ...
if α = 45°, then the equation may be written as: ...
if α = 0°, then vertical velocity is equal to 0 (Vy = 0), and that's the case of horizontal projectile motion.
Answer:
a) I₂ = 2.78 10⁻² W / m²
, b) I₃ = 9 10⁻² W/m²
, c) R₄ = 2 10⁶ m
Explanation:
The intensity of a wave is defined as the emission power per unit area
I = P / A
The unit of decibels is defined by
β = 10 log (I / Io)
With Io the hearing threshold 10⁻¹² W / m²
a) the intensity at r = 12m
Let's use the first equation
P = IA
I₁ A₁ = I₂ A₂
Let's look for intensity (I₁)
β / 10 = log I₁ / I₀
I / I₀ =
I = I₀
I = 1 10⁻¹²
I = 1 W / m²
The area of a spherical surface is
A = 4π R²
I₁ r₁² = I₂ r₂²
I₂ = I₁ R₁² / r₂²
I₂ = I₁ 2²/12²
I₂ = 1 2.78 10⁻²
I₂ = 2.78 10⁻² W / m²
b) r = 21 m
I₃ = I₁ r₁² / r₃²
I₃ = 1 2²/21²
I₃ = 9 10⁻² W/m²
c) in this case I₄ = I₀
I₁ r₁² = I₄ r₄²
R₄² = I₁ / I₄ r₁²
R₄² = 1 / 10⁻¹² 2²
R₄² = 4 10¹²
R₄ = 2 10⁶ m