Answer:
Explanation:
Let T be the temperature of an object at time t , then
dT / dt will be rate of change of temperature
According to newton's law of cooling
dT / dt = k ( T - T₂ )
where T₂ is temperature of surrounding , T is temperature of object , k is a constant .
dT / dt = k ( T - T₂ )
Given k = .4 , ambient temperature T₂ = 68⁰C
dT / dt = .4 ( T - 68 )
dT / ( T - 68 ) = .4 dt .
This is required differential equation .
Answer:
This is an incomplete question. The complete question is --
An individual white LED (light-emitting diode) has an efficiency of 20% and uses 1.0 W of electric power.
How many LEDs must be combined into one light source to give a total of 3.8W of visible-light output (comparable to the light output of a 100W incandescent bulb)?
And the answer is --
19 LEDs
Explanation:
The full form of LED is Light emitting diode.
It is given that the efficiency of the LED bulb is 20 %
1 LED uses power = 1 W
So the output power of 1 LED = 0.2 W
We need to find the power required to give a 3.8 W light.
Power required for 3.8 W = Number of LEDs required = (total required power / power required for 1 LED )
= 3.8 / 0.2
= 19
Therefore, the number of LEDs required is 19.
Answer:
This is what they said in english if everyone was wondering
Explanation:
determine the value of the velocity carried by a body whose mass is 3kg and its kinetic energy is 400Joule
Answer: is C
Expiation: you can find the answer on quizlet and it’s diverging mirror so the answer is C