<span>The correct answer is B - Light can travel in a vacuum, and its speed is constant if the source is moving or stationary.</span>
Frost will disturb the smooth flow of air over the wing, unpleasantly
distressing its lifting competence. In other words, this spoils the even flow
of air over the wings, by this means decreasing lifting capability. Also, frost
may avoid the airplane from becoming flying at normal departure speed.
The concave mirror is a spherical-shaped mirror that has an inner curved surface. Hence, option (4) is correct.
What is a concave mirror?
The concave mirrors are spherical-shaped mirrors that are painted on the outward surface. It is also known as the converging mirror, having the recessed inner reflecting surface.
- The concave mirrors are generally used for the purpose to focus the light. For that, they might have a reflecting surface, curved inwards, and the reflection of light is limited to the single focal point.
- The reflecting surface of the concave mirror has its vertex or midpoint lying farther away from the objects than the edges.
Thus, we can conclude that the surface of the concave mirror is curved inward. Hence, option (4) is correct.
Learn more about the concave mirror here:
brainly.com/question/13300307
Refer to the 2th Law of Newton
F = m. a
F = 15 x 2.8 = 42 N
