Answer:f 30
Explanation: I am not really sure but try this
 
        
             
        
        
        
Answer:
1. 0.574 kJ/kg
2. 315.7 MW 
Explanation:
1. The mechanical energy per unit mass of the river is given by:


Where:
Ek is the kinetic energy
Ep is the potential energy
v is the speed of the river = 3 m/s
g is the gravity = 9.81 m/s²
h is the height = 58 m 

Hence, the total mechanical energy of the river is 0.574 kJ/kg.
2. The power generation potential on the river is:

Therefore, the power generation potential of the entire river is 315.7 MW.
 
I hope it helps you!
 
        
             
        
        
        
The statemengt is <em>false</em>. Electromgnetic waves do not require a medium to transfer energy. They can transfer energy through vacuum (empty space with nothing in it). If electrimagnetic waves needed a medium to move through from place to place, then we could never see the sun, and also it would get very cold here.
 
        
             
        
        
        
Answer:
Part a)
When spring compressed by 2 cm
H = 1.47 m
Part b)
When spring is compressed by 4 cm
H = 5.94 m
Explanation:
Part a)
As we know that the spring is compressed and released
so here spring potential energy is converted into gravitational potential energy at its maximum height
So we will have


so we have

Part b)
Similarly when spring is compressed by 4 cm 
then we have


so we have
