What would be the best way for her to do this?
1 answer:
You might be interested in
Answer:
w = 1.14 rad / s
Explanation:
This is an angular momentum exercise. Let's define a system formed by the three bodies, the platform, the bananas and the monkey, in such a way that the torques during the collision have been internal and the angular momentum is preserved.
Initial instant. The platform alone
L₀ = I w₀
Final moment. When the bananas are on the shelf
we approximate the bananas as a point load and the distance is indicated
x = 0.45m
L_f = (m x² + I ) w₁
angular momentum is conserved
L₀ = L_f
I w₀ = (m x² + I) w₁
w₁ =
Let's repeat for the platform with the bananas and the monkey is the one that falls for x₂ = 1.73 m
initial instant. The platform and bananas alone
L₀ = I₁ w₁
I₁ = (m x² + I)
final instant. After the crash
L_f = I w
L_f = (I₁ + M x₂²) w
the moment is preserved
L₀ = L_f
(m x² + I) w₁ = ((m x² + I) + M x₂²) w
(m x² + I) w₁ = (I + m x² + M x₂²) w
we substitute
w =
w =
the moment of inertia of a circular disk is
I = ½ m_p x₂²
we substitute
w =
let's calculate
w =
w =
w = 1.14 rad / s
Answer:
a) ΔEC=-23.4kW
b)W=12106.2kW
c)
Explanation:
A)
The kinetic energy is defined as:
(vel is the velocity, to differentiate with v, specific volume).
The kinetic energy change will be: Δ ()=
Δ ()=
Where 1 and 2 subscripts mean initial and final state respectively.
Δ()=
This amount is negative because the steam is losing that energy.
B)
Consider the energy balance, with a neglective height difference: The energy that enters to the turbine (which is in the steam) is the same that goes out (which is in the steam and in the work done).
We already know the last quantity: =
Δ (
)=23400W
For the steam enthalpies, review the steam tables (I attach the ones that I used); according to that,
The exit state is a liquid-vapor mixture, so its enthalpy is:
Finally, the work can be obtained:
C) For the area, consider the equation of mass flow:
where
is the density, and A the area. The density is the inverse of the specific volume, so
The specific volume of the inlet steam can be read also from the steam tables, and its value is: , so: