Answer:
A) incandescent ligth bulb, its efficiency is about 10%
Explanation:
The incandescent bulb, that is, the well-known focus with its warm light, was one of the most useful inventions of the 19th century although its use is currently considered very inefficient. These lamps waste between 80 and 90 percent of the total electricity they consume by turning it into heat. The metal filament thus heated and which is the central part of the bulb, only converts the remaining energy into light. Its service life ranges from 750 to 1,000 hours.
This is why they are used in ovens for food preparation, because of the large amount of heat they generate.
The steam boiler in a power plant depends on the fuel that it is using, but a coal-fired power plant with modern technology its efficiency is about 40%
Electric motor are around 85-92%
In order to better understand the concept of efficiency it is as if we pay 100 dollars of gasoline for our weekly use, but of that 100 dollars the car only uses 10 dollars to do that activity the rest of the money the 90 dollars were lost because of the inefficiencies of the vehicle.
Answer:120 min
Explanation:
Given
Amanda spent 
of her time after school doing Home work
And 
of her remaining time riding her bike
It is given that she rode her bike for 45 minutes in a week
Let t be the time after school
therefore Amanda spend 
in home work and 
time is left
From remaining time she spends time riding her bike
therefore 
thus 
therefore time spent on home work is 
Answer:
0.72 Hz minimum frequency
Explanation:
When the damping is negligible,Amplitude is given as
here 
= (6.30)/(0.135) = 46.67 N/m kg
= 1.70/(0.135)(0.480) = 26.2 N/m kg
From the above equation , rearranging for ω,
⇒ ω² =46.67 ± 26.2 = 72.87 or 20.47
⇒ ω = 8.53 or 4.52 rad/s
Frequency = f
ω=2 π f
⇒ f = ω / 2π = 8.53 /6.28 or 4.52 / 6.28 = 1.36 Hz or 0.72 Hz
The lower frequency is 0.72 Hz and higher is 1.36 Hz
Answer:
2000 ohms
Explanation:
Resisters in series just add.
Rt = R1 + R2 + R3
R1 = 650 ohm
R2 = 350 ohm
R3 = 1000 ohm
Rt = 650 + 350 + 1000
Rt = 2000 ohms.
Answer:
The force acting on a body is always equal to the product of the mass of the body and its acceleration.
Explanation:
The force of a body is defined as the product of mass and acceleration of the body.
According to Newton's second law, wherever there is a change in momentum of the body for an interval of time, there is a force acting on it.
F = (mv - mu) / t
= m (v -u) /t
= m a
Where,
(v - u)/t - is the change in velocity of the body in the interval of time. It is equal to the acceleration of the body.
Hence, the equation for the force for any body becomes, F = m x a
