The complete question in the attached figure
Let
c ------------------- > is the speed of light
v ------------------- > is the speed in medium
n ------------------- > is the refractive index of medium
we know that
c/v = n
n = (3 x 10^8)/(2.04 x 10^8) = 1.47
1.47 is the refractive index of glycerol.
therefore
the answer is (4) glycerol
Hooke's Law says that F=-kx where k is the spring constant measured in N/m (newtons per meter)
Answer: angular acceleration = 
Given:
Distance from center of axis = 1.6 m
Time taken to complete one revolution = 4.7 sec
Therefore, we can evaluate the angular acceleration using the following formula:



= 
Answer:
Option B:
A child sitting on a swing.
Explanation:
When we hear the word oscillator, a good example is the pendulum bob of a grandfather clock. We can picture the motion to get a perfect understanding of its path of motion and relate it to other systems of motion in our everyday life.
An oscillator is a system that moves in such a way that it reverses its direction after a period of time. It can be seen as a "to-and-fro" motion.
From the options, a child sitting on a swing is the perfect example of an oscillating system because the child will be moving forwards and backwards, alternately reversing the direction of motion with time.