Answer: initially the packet was ascending up with the balloon.
Taking upward as positive direction;
initial velocity, u = 4.9 m/s
final velocity = v m/s
initial height, h₁ = 245 m
final height, h₂ = 0
a = -9.8 m/s²
time taken = t seconds
s = ut + 0.5at²
⇒ (h₂-h₁) = ut + 0.5at²
⇒ 0-245 = 4.9t + 0.5×(-9.8)×t²
⇒ -245 = 4.9t - 4.9t²
⇒ 4.9t² -4.9t -245 =0
Solving it, we get t = 7.59s
v = u + at = 4.9 -9.8×7.59 = 4.9 - 74.38 = -69.48 m/s
So velocity is 69.48 m/s downward
Explanation:
Answer:
24445.85 J/s
Explanation:
Area, A = 300 m^2
T = 33° C = 33 + 273 = 306 k
To = 18° C = 18 + 273 = 291 k
emissivity, e = 0.9
Use the Stefan's Boltzman law

Where, e be the energy radiated per unit time, σ be the Stefan's constant, e be the emissivity, T be the temperature of the body and To be the absolute temperature of surroundings.
The value of Stefan's constant, σ = 5.67 x 10^-8 W/m^2k^4
By substituting the values

E = 24445.85 J/s
Newton's first law. Inertia.
If it's moving, it tends to keep moving.
"Stopped" tends to stay put