Answer: 0.392 m/s
Explanation:
The Doppler shift equation is:

Where:
is the actual frequency of the sound wave
is the "observed" frequency
is the speed of sound
is the velocity of the observer, which is stationary
is the velocity of the source, which are the red blood cells
Isolating
:


Finally:

Work is done when spring is extended or compressed. Elastic potential energy is stored in the spring. Provided inelastic deformation has not happened, the work done is equal to the elastic potential energy stored.
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:



Answer:
0.241
Explanation:
resolving weight into two components and calculating force of friction in terms of coefficient of friction and then applying Newton 's law we get the value .This all has been explained in attachment
If I ask you to tell me the acceleration of gravity on Earth, you'll tell me a number. That acceleration of gravity is always that number, no matter WHEN you measure it. t doesn't change. So the graph of it is the number. The graph of a number is a horizontal line. Its equation is:
. Y = (the number) .
The correct choice is ' A ' .