Answer:
157.8 J 
Explanation:
m = mass of the cylinder = 7 kg 
h = height difference in top and bottom of the incline = 2.3 m 
g = acceleration due to gravity = 9.8 m/s²
TE = Total Energy at the bottom 
PE = Gravitational potential energy at the top 
Using conservation of energy 
Total Energy at the bottom = Gravitational potential energy at the top  
TE = PE
TE = m g h 
TE = (7) (9.8) (2.3)
TE = 157.8 J 
 
        
             
        
        
        
Answer:
Hello your question is poorly written below is the complete question
Suppose the battery in a clock wears out after moving Ten thousand coulombs of charge through the clock at a rate of 0.5 Ma how long did the clock run on does battery and how many electrons per second slowed?
answer : 
a) 231.48 days
b) n = 3.125 * 10^15
Explanation:
Battery moved 10,000 coulombs
current rate = 0.5 mA
<u>A) Determine how long the clock run on the battery. use the relation below</u>
q = i * t ----- ( 1 )
q = charge , i = current , t = time
10000 = 0.5 * 10^-3 * t 
hence  t = 2 * 10^7 secs
hence the time = 231.48  days
<u>B) Determine how many electrons per second flowed </u>
q = n*e ------ ( 2 )
n = number of electrons
e = 1.6 * 10^-19
q = 0.5 * 10^-3 coulomb ( charge flowing per electron )
back to equation 2 
n ( number of electrons ) = q / e = ( 0.5 * 10^-3 ) / ( 1.6 * 10^-19 )
hence : n = 3.125 * 10^15
 
        
             
        
        
        
Vf = Vo + at
Vf = 20 m/s
Vo = 50 m/s
a = ? 
t = 15
Therefore
20 = 50 + 15a
20 - 50 = 15a
-30 = 15a
a = -30 / 15
a = -2 m/s²
        
             
        
        
        
Explanation:
Below is an attachment containing the solution. 
 
        
             
        
        
        
Answer:
Explanation:
a ) Thermal efficiency = work output / heat input 
= .38 MW / 1 MW = .38 
OR 38%
Heat rejected at cold reservoir = heat input - work output 
1 MW - .38 MW 
= 0.62 MW. 
 b ) For reversible power output 
efficiency = T₂ - T₁ / T₂   ; T₂ is temperature of hot reservoir and T₁ is temperature of cold reservoir. 
= 1200 - 300 / 1200 = 900 / 1200 
= .75 
or 75%
rate at which heat is rejected 
= 1 - .75 x 1 
= .25 MW .