Explanation:
Initial speed of the incident water stream, u = 16 m/s
Final speed of the exiting water stream, v = -16 m/s
The mass of water per second that strikes the blade is 48.0 kg/s.
We need to find the magnitude of the average force exerted on the water by the blade. The force acting on an object is given by :

Here, 

So, the magnitude of the average force exerted on the water by the blade is 1536 N.
Complete Question
The complete question is shown on the first uploaded image
Answer:
The mass of the other block is 
Explanation:
From the question we are told that
Mass of the first block is 
The height is 
The time it takes it is
Generally from kinematic equation

Here u is the initial velocity which zero given that it was at rest initially
So

=> 
=> 
=> 
Generally from the diagram the resultant force due to the weight of the first object and the tension on the string is mathematically represented as

=> 
=> 
=> 
Generally from the diagram the resultant force due to the weight of the second object and the tension on the string is mathematically represented as

=> 
=> 
=> 
Answer:
1) 
2) 
3) 

Explanation:
Given:
width of river, 
speed of stream with respect to the ground, 
speed of the swimmer with respect to water, 
<u>Now the resultant of the two velocities perpendicular to each other:</u>



<u>Now the angle of the resultant velocity form the vertical:</u>



- Now the distance swam by the swimmer in this direction be d.
so,



Now the distance swept downward:



2)
On swimming 37° upstream:
<u>The velocity component of stream cancelled by the swimmer:</u>



<u>Now the net effective speed of stream sweeping the swimmer:</u>



<u>The component of swimmer's velocity heading directly towards the opposite bank:</u>



<u>Now the angle of the resultant velocity of the swimmer from the normal to the stream</u>:



- Now let the distance swam in this direction be d'.



<u>Now the distance swept downstream:</u>



3)
Time taken in crossing the rive in case 1:



Time taken in crossing the rive in case 2:


