The buoyant force must be greater than water.
T=2s
g=10m/s2
h=?
free fall: h=gt2/2
h= 10*4/2
h=40/2
h=20m
Answer:

Explanation:
The rotation rate of the man is:



The resultant rotation rate of the system is computed from the Principle of Angular Momentum Conservation:
![(90\,kg)\cdot (5\,m)^{2}\cdot (0.16\,\frac{rad}{s} ) = [(90\,kg)\cdot (5\,m)^{2}+20000\,kg\cdot m^{2}]\cdot \omega](https://tex.z-dn.net/?f=%2890%5C%2Ckg%29%5Ccdot%20%285%5C%2Cm%29%5E%7B2%7D%5Ccdot%20%280.16%5C%2C%5Cfrac%7Brad%7D%7Bs%7D%20%29%20%3D%20%5B%2890%5C%2Ckg%29%5Ccdot%20%285%5C%2Cm%29%5E%7B2%7D%2B20000%5C%2Ckg%5Ccdot%20m%5E%7B2%7D%5D%5Ccdot%20%5Comega)
The final angular speed is:

Velocity 0.86m/s
0.13J
Explanation:
Given parameters:
Mass = 0.343kg
distance = 5m
time taken = 5.8s
Unknown:
Velocity of mass = ?
Kinetic energy = ?
Solution:
Velocity is the rate of change of displacement with time. It is a vector quantity that shows magnitude and direction.
Mathematically;
Velocity =
Velocity =
= 0.86m/s
Kinetic energy is the energy due to the motion of a body. It is expressed mathematically as:
Kinetic energy = 
m is the mass
v is the velocity
Kinetic energy =
= 0.13J
learn more:
Kinetic energy brainly.com/question/6536722
#learnwithBrainly
Answer:
82.4 cm
Explanation:
The object and screen are kept fixed ie the distance between them is fixed and by displacing lens between them images are formed on the screen . In the first case let u be the object distance and v be the image distance
then ,
u + v = 184 cm
In the second case of image formation , v becomes u and u becomes v only then image formation in the second case is possible.
The difference between two object distance ie( v - u ) is the distance by which lens is moved so
v - u = 82.4 cm