Well, we know that the total energy in a closed system remains constant.
The problem with the story of Eva is that she is not in a closed system.
If the dark room were really a closed system, then she could press the
button or turn the switch all day, and the lamp could not light. It needs
electrical energy coming in from somewhere in order to turn on.
Let's say that Eva used her arm muscles to strike a match and light the
candle on the table. Then we would have have food energy, muscle
energy, chemical energy in the match, chemical energy in the candle,
heat and light energy coming out of the candle, heat energy soaking into
her hand, light energy bouncing off of the book and into her eyes ... all
going on during the story, and the sum total of all of them would remain
constant.
Explanation:
Because it's a power to turn the wheels of industry
Answer:
Between 120 and 180 seconds
Answer
given,
flow rate = p = 660 kg/m³
outer radius = 2.8 cm
P₁ - P₂ = 1.20 k Pa
inlet radius = 1.40 cm
using continuity equation
A₁ v₁ = A₂ v₂
π r₁² v₁ = π r₁² v₂
Applying Bernoulli's equation
v₂ = 1.97 m/s
b) fluid flow rate
Q = A₂ V₂
Q = π (0.014)² x 1.97
Q = 1.21 x 10⁻³ m³/s
Answer:
Options A, B, and C are all possible.
Explanation:
We know that the instantaneous velocity of the dog at 3:14PM is possitive to toward the flowers. But what about the acceleration to toward the flowers?
If the dog is decreasing speed at 3:14PM, it means that acceleration is negative toward the flowers, hence (since F=ma) the net force points away from the flowers.
If the dog is increasing speed at 3:14PM, it means that acceleration is positive toward the flowers, hence (since F=ma) the net force points toward the flowers.
If the dog is not increasing nor decreasing speed at 3:14PM, it means that acceleration is 0, hence (since F=ma) the net force is null and it does not point neighter to toward the flowers nor away from the flowers. This happens when the forces acting on the dog are equal to both sides.