Answer:
![\begin{array}{l|l}\text{Speed}\; \mathrm{(m\cdot s^{-1})} & \text{Minimum Height\;(m)}\\\cline{1-2}\\[-1em] 2 & 0.204\\3&0.459\\4 & 0.815\\5 & 1.27 \\6 & 1.83\end{array}](https://tex.z-dn.net/?f=%5Cbegin%7Barray%7D%7Bl%7Cl%7D%5Ctext%7BSpeed%7D%5C%3B%20%5Cmathrm%7B%28m%5Ccdot%20s%5E%7B-1%7D%29%7D%20%26%20%5Ctext%7BMinimum%20Height%5C%3B%28m%29%7D%5C%5C%5Ccline%7B1-2%7D%5C%5C%5B-1em%5D%202%20%26%200.204%5C%5C3%260.459%5C%5C4%20%26%200.815%5C%5C5%20%26%201.27%20%5C%5C6%20%26%201.83%5Cend%7Barray%7D)
.
Assumptions:
- The object is dropped in a free fall.
- There's no air resistance.
- The downward acceleration due to gravity is
Explanation:
Consider the "SUVAT" equation
,
where
is the final velocity,
is the initial velocity,
is the acceleration of the object, and
is the change in the object's position.
For example, if the bottle needs to achieve a speed of 
by the time it reaches the ground,
since the statement that the bottle is "dropped" implies a free fall.
.
Apply the previous equation to find the minimum height, :
.
Replace the value and apply the formula to find the minimum height required to reach different final speeds.
Complete question is;
A microwave oven operates at a frequency of 2400 MHz. The height of the oven cavity is 25 cm and the base measures 30 cm by 30 cm. Assume that microwave energy is generated uniformly on the upper surface of the cavity and propagates directly
downward toward the base. The base is lined with a material that completely absorbs microwave energy. The total microwave energy content of the cavity is 0.50 mJ.
Answer:
Power ≈ 600,000 W
Explanation:
We are given;
Frequency; f = 2400 Hz
height of the oven cavity; h = 25 cm = 0.25 m
base area; A = 30 cm by 30 cm = 0.3m × 0.3m = 0.09 m²
total microwave energy content of the cavity; E = 0.50 mJ = 0.5 × 10^(-3) J
We want to find the power output and we know that formula for power is;
P = workdone/time taken
Formula for time here is;
t = h/c
Where c is speed of light = 3 × 10^(8) m/s
Thus;
t = 0.25/(3 × 10^(8))
t = 8.333 × 10^(-10) s
Thus;
Power = (0.5 × 10^(-3))/(8.333 × 10^(-10))
Power ≈ 600,000 W
Explanation:
Dark Energy is a property of the entire universe. And the universe is roughly made up of 68% of this dark energy whereas dark matter makes up 27% of the universe matter.
The influence of the dark matter shows in the individual galaxies whereas dark energy acts only on the entire universe. dark matter is responsible for the gravity effect on the plants and the heavenly bodies which produces gravity force. But the dark energy is known as the anti gravity force as it is responsible for the expansion of the universe. Dark matter attracts and produces an attractive force while dark energy repels and produces a repulsive force.
Scientist believe that they exists to account for the very fact that gravity holds all the heavenly bodies and the galaxies together. They are even responsible for the fluctuation in Cosmic Microwave background. Researchers and scientist firmly believe that all the visible matter that exists may not have enough gravitational pull to hold everything together in the galaxies. And also the expanding universe strongly proves that dark energy exists in the universe.
String the·o·ry
noun
a cosmological theory based on the existence of cosmic strings.
