Answer:
Concrete absorbs visible light and re-radiates it as infrared energy.
Explanation:
As we know that concrete will not reflect 100% light incident on it but it will absorb few energy and remaining energy is reflected back.
So here when visible light incident on the concrete then few of its energy is absorbed by is and then the remaining energy is reflected back.
Since the reflected energy must be less than the energy which incident on the concrete so here we will say that the reflected waves must be of less frequency range
so here most appropriate energy range of reflected wave is infrared waves
so here correct answer will be
Concrete absorbs visible light and re-radiates it as infrared energy.
Answer:
s = 0.9689 m
Explanation:
given,
Height of fall of paratroopers = 362 m
speed of impact = 52 m/s
mass of paratrooper = 86 Kg
From from snow on him = 1.2 ✕ 10⁵ N
now using formula
F = m a
a = F/m
Using equation of motion
v² = u² + 2 a s
s = 0.9689 m
The minimum depth of snow that would have stooped him is s = 0.9689 m
Answer:
6.4 m/s
Explanation:
From the question, we are given that
Speed of the river, v(r) = 5 m/s
velocity relative to the water, v(w) = 4 m/s
Width of the river, d = 780 m
The magnitude of his velocity relative to the earth is v(m)
v(m) can be gotten by using the relation
[v(m)]² = [v(w)]² + [v(r)]²
[v(m)]² = 4² + 5²
[v(m)]² = 16 + 25
[v(m)]² = 41
v(m) = √41
v(m) = 6.4 m/s
thus, the magnitude of the velocity relative to earth is 6.4 m/s
A block of mass 3 kg slides along a horizontal surface that has negligible friction except for one section, as shown above
