The missing question is: how many photons are produced per second?
Answer:

Explanation:
The energy of a photon is given by

where
h is the Planck constant
c is the speed of light
is the wavelength of the photon
In this problem, the photons have wavelength
, so each photon has an energy of

The total energy emitted by the bulb in 1 second is
E = 100 J
Therefore, the number of photons emitted per second is

Answer:
The pushing force and the skier's mass
(A) is correct option.
Explanation:
Given that,
Mass = 64 kg
Weight = 608 N
Velocity = 21 m/s
Forward force = 45 N
We need to calculate the reaction force of the snow pushing on the skier
Using given data,
The reaction force of the snow pushing on the skier is equal to the pushing force and the skier's mass.
Hence, The pushing force and the skier's mass
(A) is correct option.
Answer:
62.5 m
Explanation:
.......................................