7 is the answer.................................
Answer:
1 N
Explanation:
From coulomb's law,
The force of attraction between two charges is inversely proportional to the square of the distance between the charges.
From the question,
Assuming the charges are the same in both case,
F ∝ /r²....................... Equation 1
Fr² = k
F'r'² = Fr²........................... Equation 2
Where F' = First Force, r'² = First distance, F = second force, r² = second distance.
make F the subject of the equation,
F = F'r'²/r².................... Equation 3
Given: F' = 4 N, r' = 3 m, r = 6 m
Substitute into equation 3
F = 4(3²)/6²
F = 36/36
F = 1 N
Answer:
Part A) 3899 kPa
Part B) 392.33 kJ/kg
Part C) 0.523
Part D) 495 kPa
Explanation:
Part A
First from the temperature at state 1 the relative specific volume and the internal energy at that state are determined from:
= 214.07 kJ/kg

= 621.2
The relative specific volume at state 2 is obtained from the compression ratio:

=
=621.2/ 8
= 77.65
From this the temperature and internal energy at state 2 can be determined using interpolation with data from A-17(table):
= 673 K
= 491.2 kJ/kg
The pressure at state 2 can be determined by manipulating the ideal gas relations at state 1 and 2:
= 
= 95*8*673/300
= 1705 kPa
Now from the energy balance for stage 2-3 the internal energy at state 3 can be obtained:

= 1241.2 kJ/kg
From this the temperature and relative specific volume at state 3 can be determined by interpolation with data from A-17(table):
= 1539 K
= 6.588
The pressure at state 3 can be obtained by manipulating the ideal gas relations for state 2 and 3:

= 3899 kPa
<u>Part B</u>
The relative specific volume at state 4 is obtained from the compression ratio:

= 52.7
From this the temperature and internal energy at state 4 can be determined by interpolation with data from A-17:
=775 K
= 571.74 kJ/kg
The net work output is the difference of the heat input and heat rejection where the heat rejection is determined from the decrease in internal energy in stage 4-1:

<u>Part C </u>
The thermal efficiency is obtained from the work and the heat input:
η=
=0.523
<u>Part D </u>
The mean effective pressure is determined from its standard relation:
MEP=
=
=
=495 kPa
Answer:
KE = 1.05 x105 Joules
Explanation:
KE = 4 * (1.04653 x 105 J) = 4.19 x 105 Joules.
Answer:
201.6 N
Explanation:
m = mass of disk shaped merry-go-round = 125 kg
r = radius of the disk = 1.50 m
w₀ = Initial angular speed = 0 rad/s
w = final angular speed = 0.700 rev/s = (0.700) (2π) rad/s = 4.296 rad/s
t = time interval = 2 s
α = Angular acceleration
Using the equation
w = w₀ + α t
4.296 = 0 + 2α
α = 2.15 rad/s²
I = moment of inertia of merry-go-round
Moment of inertia of merry-go-round is given as
I = (0.5) m r² = (0.5) (125) (1.50)² = 140.625 kgm²
F = constant force applied
Torque equation for the merry-go-round is given as
r F = I α
(1.50) F = (140.625) (2.15)
F = 201.6 N