Answer:(a)10 ft/s
(b)4 ft/s
Explanation:
Given
height of light 
height of man

From diagram



differentiate both sides

Tip of shadow is moving at the rate of

(b)rate at which length of his shadow is changing
Length of shadow is 
differentiating w.r.t time


The answer would be intoduction hope this really helped
Answer:
The magnetic field strength and the electrons' energy are 0.077 T and 0.8906 eV.
Explanation:
Given that,
Diameter = 2.62 mm
Frequency = 2.15 GHz
(A). We need to calculate the magnetic field strength
Using formula of the magnetic field strength

Where, f = frequency
e = charge of electron
Put the value into the formula


(B). We need to calculate the energy of electron
Using formula of energy



The energy in eV



Hence, The magnetic field strength and the electrons' energy are 0.077 T and 0.8906 eV.
Answer:
Water normally freezes at 0°C (32°F). Salt lowers the freezing temperature. (That is, it can remain a liquid at much lower temperatures.)
When sprinkled on ice, the salt lowers the freezing temperature of the water which effectively melts the ice when the salt dissolves into it. There is a limit to how low it can reduce the temperature, though. If the temperature drops below -9°C (15°F), it's too cold for the salt to dissolve into the ice.
When making ice cream, the salt lowers the temperature of the ice and water sufficiently enough to freeze the cream.