Answer:
422.36 N
Explanation:
given,
time of rotation = 4.30 s
T = 4.30 s
Assuming the diameter of the ring equal to 16 m
radius, R = 8 m


v = 11.69 m/s
now, Force does the ring push on her at the top





N = 422.36 N
The force exerted by the ring to push her is equal to 422.36 N.
Answer:
Explanation:
Given

angular velocity 
Combined moment of inertia of stool,student and bricks 
Now student pull off his hands so as to increase its speed to suppose
rev/s
After Pulling off hands so final moment of inertia is

Conserving angular momentum as no external torque is applied




Answer:
Power input, P = 2880 watts
Explanation:
It is given that,
Voltage of the motor, V = 240 V
Current required, I = 12 A
Weight lifted, W = 2000 lb
It is lifting at a speed of 25 ft/min. We need to find the power input to the motor. The product of current and voltage is called power input of the motor.


P = 2880 watts
So, the power input of the motor is 2880 watts. Hence, this is the required solution.
Answer:
Option D
The air pressure inside the car is greater than the pressure outside.
Explanation:
When considering airflow over and around a surface, from Bernoulli's equation, air flow regions with higher velocity have a lower pressure, and regions with lower velocity have a higher pressure.
The air outside the convertible is moving faster than the air inside the convertible. This leads to a higher pressure zone just below the surface of the roof (inside the car) causing the roof of the convertible to bulge upwards