Answer:
(a) 5.04 eV (B) 248.14 nm (c) 
Explanation:
We have given Wavelength of the light \lambda = 240 nm
According to plank's rule ,energy of light


Maximum KE of emitted electron i= 0.17 eV
Part( A) Using Einstien's equation
, here
is work function.
= 5.21 eV-0.17 eV = 5.04 eV
Part( B) We have to find cutoff wavelength



Part (C) In this part we have to find the cutoff frequency

Answer:
He requires 1 gram of mass.
Explanation:
The density is defined as:
(1)
Where m is the mass and V is the volume.
Then, m can be isolated from equation 1 in order to determine the mass.
(2)
Hence, he requires 1 gram of mass.
Answer:
the total momentum is 8 .2 kg m/s in north direction.
Explanation:
given,
mass(m₁) 3.00 kg, moving north at v₁ = 3.00 m/s
mass(m₂) 4.00 kg, moving south at v₂ = 3.70 m/s
mass(m₃) 7.00 kg, moving north at v₃ = 2.00 m/s
north as the positive axis
south as the negative axis
now
total momentum = m₁v₁ + m₂ v₂ + m₃ v₃
total momentum = 3 x 3 - 4 x 3.7 + 7 x 2
= 9 - 14.8 + 14
= 8 .2 kg m/s
hence, the total momentum is 8 .2 kg m/s in north direction.
Time = (distance) / (speed)
Time = (4.12x10^16 m) / (3 x10^8 m/s)
Time = 1.37 x 10^8 seconds
Divide the seconds by 86,400 to get days. Then divide the days by 365 to get years.
Time = about 4.35 years