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To compute for the change in potential energy, the equation would be:
delta PE = mg*delta h
delta PE = 0.5*9.81*(2-1.8)
delta Pe = 0.98 J
The potential energy is converted to kinetic energy.
Answer:
The resistivity of the material used to make the rod is ρ= 7.5 * 10⁻⁷ Ω.m
Explanation:
R= 0.2 Ω
L= 0.8 m
S= 1.5mm*2mm= 3 mm² = 3 * 10⁻⁶ m²
ρ = (R*S)/L
ρ= 7.5 * 10⁻⁷ Ω.m
The first answer in the blank is pours out of you, the second answer in the space provided is diffuse. It is because a person who has an effusive personality will likely pour out his or her emotions while the motor oil will likely diffuse if this has been spilled out of the can.
In Burglar alarm, LDR acts an AND gate.
Answer: C
Explanation
The LDR is light dependent resistor. The principle used in the working of LDR is that the resistance is inversely proportional to the intensity of light falling on the diode.
In burglar alarm, LDR diode is combined with an IC 555.
Normally an LED source is made to be incident on the LDR diode with same intensity such that the resistance will be maintained constant.
As the LDR is connected with IC, the voltage will be high when light is falling on the diode.
The IC will give only two output states that is high and low. This confirms that LDR in burglar alarm act as AND gate.
As the thief enters and crosses the LED light, the intensity of the light falling on the diode will decrease leading to decrease in the voltage which will cause the alarm to beep.
Answer:
How: It will have a very different chemical composition.
Why: Because the interstellar medium at the beginning of universe were compounded only of Hydrogen and Helium.
Explanation:
Once the Big Bang passed and the universe began its expansion, the temperature started to decrease, what allowed the combination of hydrogen and helium. Therefore, the chemical composition of the molecular cloud in which the first stars were formed only held those elements.
If the Sun and the solar system were formed from a molecular cloud with that composition, it will both have an absence of metallic elements (elements heavier than helium), since all of them are formed through nuclear reactions in the core of the stars, and each time a star dies, the interstellar medium for the next generation is enriched.
Key elements for life as Carbon, Nitrogen, Oxygen, Phosphorus and Sulfur will be missing for that hypothetical scenario.
For example, the lack of O3 (ozone) in the atmosphere of earth will allow that ultraviolet light hits the earth surface.
