What is an object’s acceleration due to gravity on earth?
2 answers:
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Answer:
The mass of the Al-duckie should be 30 kg.
Explanation:
We will use the first law of thermodynamics:
ΔU = m·Cv·ΔT
Since the specific heat of water is 4.185 J(gºC), the change in the water's internal energy would be:
ΔU = 100 kg · 4.185 J(gºC) · (42ºC - 38ºC) = 1674 KJ
Given that no heat is lost, all the internal energy that the water loses while cooling down will transfer to the duckie. So, if the duckie has ΔU = 1674 KJ and its final temperature is the desired 38 ºC, we can calculate its mass using the first law again:
Answer:
speed of the Jon visiting parents = 56 mph
speed of the Jon when returning from home = 56 - 14 = 42 mph
Explanation:
given,
distance of Jon parent's house = 648 mile
avg speed when he was visiting his parent's house be 'x' mph
avg speed when he is returning from his parent's house be 'x-14' mph
total time taken = 27 hours
total distance = speed × time
648 = x × t₁
648 = ( x - 14 ) × t₂
t = t₁ + t₂
x² - 62 x + 336 = 0
x² - 56 x - 6 x + 336 = 0
(x - 56 )(x - 6)=0
on solving
x = 56 ,6
hence, speed of the Jon visiting parents = 56 mph
speed of the Jon when returning from home = 56 - 14 = 42 mph