Answer:
c. 1600J
Explanation:
The loss in potential energy of the boy is given by:

where
m = 40 kg is the mass of the boy
g = 9.8 m/s^2 is the acceleration of gravity
is the total change in the height of the boy (4 metres + 2 cm due to the compression of the spring)
Substituting, we find

Answer:
The answer is 10.857mJ
Explanation:
The energy stored in this solenoid is given by the below mentioned equation,

where L the inductance of this solenoid is given by the below mentioned equation,

Plugging this into the energy equation you obtain the equation for the total energy stored in the magnetic field of the solenoid, given by,

where
is the permeability of free space which equals to
. Plugging all the quantities into the above equation from the data in the question after converting to standard units. of meters instead of centimeters, we get for the energy stored in the coil,

Answer:
B) The cosmic background radiation is expected to contain spectral lines of hydrogen and helium, and it does.
Explanation:
It looks blue as it is only reflecting blue light
Answer:
Because a person may be pulled in the direction of the moving train. Thereby causing accident
Explanation:
According to Daniel Bernoulli's theorem, he was widely known as a Mathematician. He stated that due to the higher velocity of a moving train, there is higher kinetic energy in terms of volume around it, while the air pressure between the person and the train becomes lower.
As a result, a person near a moving train may be pulled in the direction of the moving train. Thereby causing accidents that may lead to death.