Answer:
1) Recollapsing universe
2) critical universe
3) Coasting universe
Explanation:
According to the smallest ration (ratio actual mass density to current density) to largest ration, rank of models for expansion of universe are
1) Recollapsing universe -in this, metric expansion of space is reverse and universe recollapses.
2) critical universe - in this, expansion of universe is very low.
3) Coasting universe - in this, expansion of universe is steady and uniform
Answer:

Explanation:
first write the newtons second law:
F
=δma
Applying bernoulli,s equation as follows:
∑
Where,
is the pressure change across the streamline and
is the fluid particle velocity
substitute
for {tex]γ[/tex] and
for 

integrating the above equation using limits 1 and 2.

there the bernoulli equation for this flow is 
note:
=density(ρ) in some parts and change(δ) in other parts of this equation. it just doesn't show up as that in formular
Answer:
you must throw 3 snowballs
Explanation:
We can solve this exercise using the concepts of conservation of the moment, let's define the system as formed by the refrigerator and all the snowballs. Let's write the moment
Initial. Before bumping that refrigerator
p₀ = n m v₀
Where n is the snowball number
Final. When the refrigerator moves
pf = (n m + M) v
The moment is preserved because the forces during the crash are internal
n m v₀ = (n m + M) v
n m (v₀ - v) = M v
n = M/m v/(vo-v)
Let's look for the initial velocity of the balls, suppose the person throws them with the maximum force if it slides in the snow (F = 100N), let's use the second law and Newton
F = m a
a = F / m
The distance the ball travels from zero speed to maximum speed is the extension of the arm (x = 1 m), let's look kinematically for the speed of the balls when leaving the arm
v₁² = v₀² + 2 a x
v₁² = 0+ 2 (100/1) 1
v₁ = 14.14 m / s
This is the initial speed for the crash
v₀ = v = 14.14 m / s
Let's calculate
n = M/m v/ (v₀-v)
n = 10/1 3 / (14.14 -3)
n = 2.7 balls
you must throw 3 snowballs
The velocity of projectile has 2 components, horizontal component vcosθ and vertical component vsinθ, where v is the velocity of projection and θ is the angle between +ve X-axis and projectile motion.
In case 1, θ = 90⁰
So horizontal component is vcos90 = 0
Vertical component at maximum height = 0
So velocity at maximum height = 0 m/s
In case 2, θ = 45⁰
So horizontal component is 141cos45 = 100m/s
Vertical component at maximum height = 0
So velocity at maximum height = 100 m/s