D, I hope this is correct!
Answer:
A) 1000 joules
Explanation:
In general work is given by the equation:
(1)
A) With the displacement and the force applied, because the force and the displacement are parallel (the crate is pushed horizontally) is simply , and because the path is a straight line and the force is constant work is:
(2),
B) The work-energy theorem says that the total work on a body is equal to the change on kinetic energy:
(3)
The total work on the crate is the work done by the push and plus the work of the friction (4) , as (A) because forces are parallel to the displacement (5) and (6), the due friction always has negative sign because is opposite to the displacement, using (6), (5) and (4) on (3):
(3)
C) The energy is lost by friction, so the amount of energy turned into heat is the work the friction does:
(3)
Answer:
The specific heat addition is 773.1 kJ/kg
Explanation:
from table A.5 we get the properties of air:
k=specific heat ratio=1.4
cp=specific heat at constant pressure=1.004 kJ/kg*K
We calculate the pressure range of the Brayton cycle, as follows
n=1-(1/(P2/P1)^(k-1)/k))
where n=thermal efficiency=0.5. Clearing P2/P1 and replacing values:
P2/P1=(1/0.5)^(1.4/0.4)=11.31
the temperature of the air at state 2 is equal to:
P2/P1=(T2/T1)^(k/k-1)
where T1 is the temperature of the air enters the compressor. Clearing T2
11.31=(T2/290)^(1.4/(1.4-1))
T2=580K
The temperature of the air at state 3 is equal to:
P2/P1=(T3/T4)^(k/(k-1))
11.31=(T3/675)^(1.4/(1.4-1))
T3=1350K
The specific heat addition is equal to:
q=Cp*(T3-T2)=1.004*(1350-580)=773.1 kJ/kg
I think the answer would be C, because to me that's one that makes sense, I hope that I could help, Have a great Thursday!
Answer:
a) F_b = 6.62 N
b) F_net = 5.583 N
Explanation:
Given:
- Conditions of He gas: T = 0 C , P = 1 atm , ρ = 0.179 kg/m^3
- The mass of balloon m = 0.012 kg
- The radius of balloon r = 0.5 m
Find:
a)What is the magnitude of the buoyant force acting on the balloon?
b)What is the magnitude of the net force acting on the balloon?
Solution:
- The buoyant force F_b acting on the balloon is equal to the weight of the air it displaces.The mass of the displaced air ρ*V is the volume of the balloon times the density of the. Multiplying that by acceleration due to gravity gives its weight.
F_b = ρ*V*g
F_b = 4*ρ*g*pi*r^3 / 3
F_b = 4*1.29*9.81*pi*.5^3 / 3
F_b = 6.62 N
- The net force will be the difference between the balloon’s weight and the buoyant force. The weight of the balloon is the density of the helium times the volume of the balloon added to the mass of the empty balloon.
F_g = ρ*V*g + m*g
F_g = 4*ρ*g*pi*r^3 / 3 + 0.012*9.81
F_g = 4*0.179*9.81*pi*.5^3 / 3 + 0.012*9.81
F_g = 1.037 N
- The net force is the difference between weight and buoyant force
F_net = F_g - F_b
F_net = 6.62 - 1.037
F_net = 5.583 N