The gravity is pushing rhe boat down
        
                    
             
        
        
        
<span>ultraviolet
Have a great day!</span>
        
                    
             
        
        
        
Answer:
Explanation:
radius of circle r = 0.9 m.
(a ) In a motion on circular path , work done is zero because force ( centripetal force ) acts perpendicular to displacement .
( b )
Tension in string T = m ω²r 
Putting the values 
60 = .072 x ω² x 0.9 
ω² = 926
ω = 30.4 rad /s 
angle made in 20 revolutions θ = 20 x 2π = 126.6 rad
time taken = θ / ω
= 126.6 / 30.4
= 4.16 s . 
 
        
             
        
        
        
The amount or cost that the user of the energy-efficient bulb save during 100h of use will be $0.319.
<h3>How to calculate the cost?</h3>
For the 11.0W bulb, it should be noted that the value will be:
= 11.0 × 100 × (1/1000) × 0.110
= $0.121
The 40W bulb will be:
= 40 × 100 × (1/1000) × 0.110
= $0.44
Therefore, the amount that will be saved will be:
= $0.44 - $0.121
= $0.319
Learn more about cost on:
brainly.com/question/25109150
#SPJ4