Answer:
Explanation:
ΔE = Δm × c^2
where,
ΔE = change in energy released with respect to change in mass
= 1.554 × 10^3 kJ
= 1.554 × 10^6 J
Δm = change in mass
c = the speed of light.
= 3 × 10^8 m/s
Equation of the reaction:
2H2 + O2 --> 2H2O
Mass change in this process, Δm = 1.554 × 10^6/(3 × 10^8)^2
= 1.727 × 10^-11 kg
The change in mass calculated from Einstein equation is small that its effect on formation of product will be negligible. Hence, law of conservation of mass holds correct for chemical reactions.
Complete question:
A pendulum of length L = 48.5 cm and mass m = 169 g is released from rest when the cord makes an angle of 65.4° with the vertical. What is the speed of the mass (m/s) upon reaching its lowest point?
Answer:
The speed of the mass upon reaching its lowest point is 2.36m/s
Explanation:
To obtain the speed of the mass upon reaching its lowest point, we apply the principle of conservation of mechanical energy. At the lowest point, the kinetic energy of the pendulum is maximum and at the highest point, the vertical displacement is maximum, thus potential energy is maximum.
Kinetic energy at the lowest point = Potential energy at the highest point

From my explanation above, h is the vertical displacement, when potential energy of the pendulum is maximum. Considering a right angled triangle, this vertical displacement, h is the adjacent of the triangle, and it is equal to
L - Lcosθ.
h = 48.5 - 48.5cos(65.4) = 28.31 cm = 0.2831 m

Therefore, the speed of the mass upon reaching its lowest point is 2.36m/s
<h2>
Answer:</h2>
• Point charge (Q) = 10 μC = 10 × 10⁻⁶ C
• Potential (V) = 1000 V
• Distance (r) = ?







Hence,the option B) 90 m is the correct answer.
Answer:
C.O.P = 1.49
W = 335.57 joules
Explanation:
C.O.P = coefficient of performance = (benefit/cost) = Qc/W ...equ 1 where C.O.P is coefficient of performance, Qc is heat from cold reservoir, w is work done on refrigerator.
Qh = Qc + W...equ 2
W = Qh - Qc ...equ 3 where What is heat entering hot reservoir.
Substituting for W in equ 1
Qh/(Qh - Qc) = 1/((Qh /Qc) -1) ..equ 4
Since the second law states that entropy dumped into hot reservoir must be already as much as entropy absorbed from cold reservoir which gives us
(Qh/Th)>= (Qc/Tc)..equ 5
Cross multiple equ 5 to get
(Qh/Qc) = (Th/Tc)...equ 6
Sub equ 6 into equation 4
C.O.P = 1/((Th/Tc) -1)...equ7
Where Th is temp of hot reservoir = 493k and Tc is temp of cold reservoir = 295k
C.O.P = 1/((493/295) - 1)
C.O.P = 1.49
To solve for W= work done on every cycle
We substitute C.O.P into equ 1
Where Qc = 500 joules
1.49 = 500/W
W = 500/1.49
W = 335.57 joules