Answer:
10.93 rad/s
Explanation:
If we treat the student as a point mass, her moment of inertia at the rim is

So the system moment of inertia when she's at the rim is:

Similarly, we can calculate the system moment of inertia when she's at 0.456 m from the center

We can apply the law of angular momentum conservation to calculate the post angular speed when she's 0.456m from the center:


Explanation:
The speed of a wave is given by :
......(1)
(i) Here, the wavelength of a sound wave in air reduces by a factor of 3. Equation (1) becomes :

Wavelength and frequency are inversely proportional to each other. So, if wavelength of a sound wave in air reduces by a factor of 3, then the frequency will increases by a factor of 3.
(ii) It remains the same.
Answer:
The driver was not telling the truth because it is not possible for a car to hit another car from behind and generate a force to the sides that deflects it from its path.
Explanation:
First, we analyze the driver's statement.
The driver when arriving at the curve, is collided from behind by another car and deviates from his path and crashes into a tree. For the car to go to the tree there must be a force towards the tree.
The net force that causes the car to deviate must be formed by the sum of the motion vector of the first car plus the force that is directed towards the tree.
Here we verify that a car hitting from behind will not generate a force to the sides, but will generate a force in the same direction that the car moves, forward.
Solution :
Given
Diameter of the roulette ball = 30 cm
The speed ball spun at the beginning = 150 rpm
The speed of the ball during a period of 5 seconds = 60 rpm
Therefore, change of speed in 5 seconds = 150 - 60
= 90 rpm
Therefore,
90 revolutions in 1 minute
or In 1 minute the ball revolves 90 times
i.e. 1 min = 90 rev
60 sec = 90 rev
1 sec = 90/ 60 rec
5 sec = 
= 75 rev
Therefore, the ball made 75 revolutions during the 5 seconds.