Answer: Option (B) is the correct answer.
Explanation:
Convection is defined as a process in which a fluid (liquid or gas) is heated and the cooler liquid (more dense) settles or sinks at the bottom whereas a hotter material (less dense) will rises to the top.
For example, ice being less dense (cooler material) will float in a lake whereas liquid water being more dense will sink at the bottom.
Thus, we can conclude that situation in which convection currents most likely occur is within the water in a lake as ice forms on the top.
 
        
                    
             
        
        
        
Higher voltage means faster rotation.  Changing the voltage polarity changes the direction of the motor.
        
             
        
        
        
Ans. 5 X 10^6 
Explanation: 
Here,^ represents 6 times 10 and 5 is multiplied. That is 5000 000. 
Hope this helps
        
             
        
        
        
Answer:
V= 33.98 m/s
Explanation:
Given that
Horizontal speed ,u= 17 m/s
Time taken by rockets to strike the water ,t= 3 s
We know that acceleration due to gravity ,g= 9.81 m/s²
There is no any acceleration in the horizontal direction that is why the horizontal veloity will remain constant.
In the vertical direction
vy = uy+ g t
Initial velocity in vertical direction is 0 m/s.
vy= 0+ 9.81 x 3 
vy = 29.43 m/s
The resultant velocity


V= 33.98 m/s
 
        
             
        
        
        
We use the formula, to calculate the average speed of the round trip,

Here,  , is total distance covered by plane in total time,
, is total distance covered by plane in total time,  .
.
For the round trip,

 .
.
Thus,
 .
.