Answer:
Yes, I'm pretty sure it is. That's why I don't click on it!
Answer:

Explanation:
Given that,
A system can detect objects as small as 19.1 cm i.e. 0.191 m. It is the wavelength.
We know that,
Frequency, 
So,

So, the frequency of such a system is equal to
.
Answer:
the mass of water is 0.3 Kg
Explanation:
since the container is well-insulated, the heat released by the copper is absorbed by the water , therefore:
Q water + Q copper = Q surroundings =0 (insulated)
Q water = - Q copper
since Q = m * c * ( T eq - Ti ) , where m = mass, c = specific heat, T eq = equilibrium temperature and Ti = initial temperature
and denoting w as water and co as copper :
m w * c w * (T eq - Tiw) = - m co * c co * (T eq - Ti co) = m co * c co * (T co - Ti eq)
m w = m co * c co * (T co - Ti eq) / [ c w * (T eq - Tiw) ]
We take the specific heat of water as c= 1 cal/g °C = 4.186 J/g °C . Also the specific heat of copper can be found in tables → at 25°C c co = 0.385 J/g°C
if we assume that both specific heats do not change during the process (or the change is insignificant)
m w = m co * c co * (T eq - Ti co) / [ c w * (T eq - Tiw) ]
m w= 1.80 kg * 0.385 J/g°C ( 150°C - 70°C) /( 4.186 J/g°C ( 70°C- 27°C))
m w= 0.3 kg
Answer:
41°
Explanation:
refractive index of glass, n = 1.52
For total internal reflection, the angle of refraction in rarer medium is 90°.
r = 90°
Let the angle of refraction in denser medium, that means in glass is i.
By use of Snell's law
refractive index of rarer medium with respect to denser medium, that means refractive index of air with respect to glass = 1 / n
And



i = 41°
Thus, the angle of incidence should be 41°.