Answer:
Explanation:
(a) Work done, W = 1.82 x 10^4 J 
(b) internal energy, U = - 4.07 x 10^4 J ( as it decreases)
(c) According to the first law of thermodynamics  
Q = W + U
Q = 1.82 x 10^4 - 4.07 x 10^4 
Q = - 2.25 x 10^4 J
 
        
             
        
        
        
During convection of air currents,  cool air sinks.  <em>(b)</em>
 
        
                    
             
        
        
        
Answer:

Explanation:
To solve this problem, we can use the following suvat equation:

where
 is the vertical displacement of the frog
 is the vertical displacement of the frog
 is the initial vertical velocity
 is the initial vertical velocity
t is the time
a is the acceleration
We have chosen this formula because apart from  , all the other quantities are known. In fact:
, all the other quantities are known. In fact:
 is the vertical displacement
 is the vertical displacement
t = 2 s is the total time of flight
 is the acceleration due to gravity (negative because it is downward)
 is the acceleration due to gravity (negative because it is downward)
Therefore, solving for  , we find the initial velocity of the frog:
, we find the initial velocity of the frog:

 
        
             
        
        
        
Answer:
The average power  provided by the tension in the cable pulling the lift is = 714 W
Explanation:
Given data 
Mass = 71 kg
Change in height = 123 m
When the lift moves in upward direction then in that case kinetic energy is constant & only potential energy changes.
Change in potential energy Δ PE = m g (  )
 )
Δ PE = 71 × 9.81 × 123 
Δ PE = 85670.73 J 
Time = 2 min = 120 sec
So average power is given by



Therefore the average power  provided by the tension in the cable pulling the lift is = 714 W