Answer:
(a)

(b)

(c) 
Explanation:
According to the Wein's displacement law

Where, T be the absolute temperature and b is the Wein's displacement constant.
b = 2.898 x 10^-3 m-K
(a) T = 37°C = 37 + 273 = 310 K



(b) T = 1500°C = 1500 + 273 = 1773 K



(c) T = 5800 K



Not sure what the given options are, but the answer is the horizontal component. This is given by Force x cos(angle), or Fcos(θ), where θ is the angle. In this case that would be 20cos(30) = 17.32N
Answer:
When the net external force is zero
Explanation:
We can answer to this question by referring to Newton's Second Law, which can be written in the following form

where
F is the net external force acting on a system
is the change in momentum of the system
is the time interval
When the total momentum of a system is conserved (so, it does not change), its variation is zero:

In order to satisfy this condition, we see from the formula that we must also have
F = 0
so the net external force acting on the system must be zero.
Answer:
The energy of one photon is 2.21x10⁻²⁴ J. Multiplied by 10²⁵ is 22.10 J.
Explanation:
The energy (E) of a photon is:

Where:
h: is the Planck's constant = 6.62x10⁻³⁴ J.s
λ: is the wavelength of the radiation = 8.97 cm
c: is the speed of light = 3.00x10⁸ m/s

Hence, the energy of one photon is 2.21x10⁻²⁴ J.
Now, if we multiply the answer by 10²⁵ we have:

I hope it helps you!