Answer:
= 308.5 N
Explanation:
acceleration of rocket for safe landing


= initial velocity
=final Velocity
m = mass of rocket

-5.625 
Upward force
F - mg = ma
F = ma+ mg
F = m(a+g)
m= mass
a = 5.625 
g = 9.8
= 20(5.625
+ 9.8
)
= 308.5 N
To solve this problem we will apply the concept related to the conservation of the Momentum. We will then start considering that the amount of initial momentum must be equal to the amount of final momentum. Considering that all the objects at the initial moment have the same initial velocity (Zero, since they start from rest) the final moment will be equivalent to the multiplication of the mass of each object by the velocity of each object, so
Initial Momentum = Final Momentum

Here,
= mass of Raft
= Mass of swimmers 1
= Mass of swimmers 2
= Initial velocity (of the three objects)
= Velocity of Raft
Replacing,

Solving for 


Therefore the velocity the rarft start to move is 0.3618m/s
When it's at its highest temperature
Answer:
(a) 83475 MW
(b) 85.8 %
Explanation:
Output power = 716 MW = 716 x 10^6 W
Amount of water flows, V = 1.35 x 10^8 L = 1.35 x 10^8 x 10^-3 m^3
mass of water, m = Volume x density = 1.35 x 10^8 x 10^-3 x 1000
= 1.35 x 10^8 kg
Time, t = 1 hr = 3600 second
T1 = 25.4° C, T2 = 30.7° C
Specific heat of water, c = 4200 J/kg°C
(a) Total energy, Q = m x c x ΔT
Q = 1.35 x 10^8 x 4200 x (30.7 - 25.4) = 3 x 10^12 J
Power = Energy / time
Power input =
Power input = 83475 MW
(b) The efficiency of the plant is defined as the ratio of output power to the input power.


Thus, the efficiency is 85.8 %.