The answer to this question is B I think
Answer:
W = - 5.01 10¹⁰ J
Explanation:
Work is defined by the expression
W = ∫ F.dr
Where the blacks indicate vectors, in the case the force is radial and the distance is also radial, whereby the scalar producer is reduced to an ordinary product
W = ∫ F dr
W = G m₁m₂ ∫ 1 /r² dr
W = G m₁ m₂2(-1 / r)
We evaluate between the lower limits r = Re and upper r = ∞
W = G m₁m₂ (-1 / Re + 1 / ∞)
W = - G m₁ m₂ / Re
Let's calculate
W = - 6.67 10⁻¹¹ 800 5.98 10²⁴ / 6.37 10⁶
W = - 5.01 10¹⁰ J
The answer is "A" Endothermic. Hope that helped :)
Answer:

Explanation:
From frequency of oscillation

Initially with the suspended string, the above equation is correct for the relation, hence

where k is force constant and m is the mass
When the spring is cut into half, by physics, the force constant will be doubled as they are inversely proportional

Employing f2/ f1, we have

Answer:
20 Ω
Explanation:
Voltage, current, and resistance are related by Ohm's law:
V = IR
40 V = (4 A) R
R = 10 Ω
The total resistance of the circuit is 10 Ω.
Resistors in parallel have a total resistance of:
1/R = 1/R₁ + 1/R₂
1 / (10 Ω) = 1 / (20 Ω) + 1/R₂
R₂ = 20 Ω