Answer:
4
Explanation:
Waves that are squished have higher frequency. It has short wavelength.
Answer:
Option C and D only
Explanation:
Option A is incorrect because refractive index of a material is the ratio of speed of light in vacuum to the speed of light in a any given medium
Option B is correct as the speed of light in vacuum is always greater than the speed of light in any given medium.
Option C is correct
Option D is incorrect
Option E is incorrect because the denser the medium the more is the refractive index. Water is denser than air, hence it should have more refractive index as compared to that of air.
They send out waves differently and cannot be heard easily
Answer:
4.15 m/s
Explanation:
Its given that acceleration is 0.1 m/s² with a direction opposite to the velocity. Since, the direction of acceleration is opposite to the velocity, this gives us a hint that the velocity is decreasing and so acceleration would be negative.
i.e.
acceleration = a = - 0.1 m/s²
Distance covered = S = 6m
Velocity after covering 6 meters = Final velocity =
= 4 m/s
We need to find the initial speed, which will be the same as the magnitude of initial velocity.
Initial velocity =
= ?
3rd equation of motion relates the acceleration, distance, final velocity and initial velocity as:

Using the known values in the formula, we get:

Thus, the initial speed of the ball was 4.15 m/s