Answer:
(a) t = 1.67 s
(b) s₂ = 45 m
Explanation:
Here, we use the formula:
s = vt
FOR Seth:
s₁ = v₁t₁
where,
s₁ = distance covered by Seth
v₁ = speed of Seth = 9 m/s
t₁ = time taken by Seth
FOR Mack:
s₂ = v₂t₂
where,
s₂ = distance covered by Mack
v₂ = speed of Mack = 27 m/s
t₂ = time taken by Mack
since, initially Mack is 30 m behind Seth. Therefore,
(a)
s₂ = s₁ + 30 m
using formulae:
v₂t₂ = v₁t₁ + 30 m
but, the time of catching is same for both (t₁ = t₂ = t)
v₂t = v₁t + 30 m
using values:
(27 m/s)t - (9 m/s)t = 30 m
t = (30 m)/(18 m/s)
<u>t = 1.67 s</u>
(b)
s₂ = v₂t
using values:
s₂ = (27 m/s)(1.67 s)
<u>s₂ = 45 m</u>
Answer:
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The stone gets heat energy from fire and moves this heat energy or thermal energy to water as it cools off and the water warms up. Heat moves or is transferred spontaneously from the hot stone into the cold water. Eventually, the stone and water have the same temperature and water becomes heated. At the time of heat flowing out of the stone into the water, the heat energy became less ordered, due to spreading out through both the stone and the water. This is a net increase in entropy which is the second law of entropy.
In normal fission reactors, the fuel used to start the nuclear fission is Uranium-235.
Generally, fuel rods enriched with uranium-235 are used to start the fission. When a nucleus of uranium-235 absorbs a neutron, it becomes unstable and then it breaks apart, producing two smaller nuclei, several neutrons and energy. The additional neutrons produced in the reaction are then absorbed by other nuclei of uranium-235, triggering other fission reactions, and so on.
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