The power is 833.3 W
Explanation:
First of all, we need to calculate the work done in lifting the barbell, which is equal to the change in gravitational potential energy of the barbell:
where
mg = 1250 N is the weight of the barbell
h = 2 m is the change in height
Substituting,
Now we can calculate the power, which is equal to the work done per unit time:
where
W = 2500 J is the work done
t = 3 s is the time taken
Substituting,
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Answer:
My best friend lol cuz since quarantine i didn't see her
First is melts then it expands next it gets cooler Finally it gains ener. Hope this helps you out.
Answer: B
Explanation:
It's not the time it took to heat the substance, so that rules out A and C.
This means that we only have to choose between
B. the area of contact
D. the area of the substances
(since everything else in each of those answers are the same)
Area of contact matters more (e.g. an object with greater surface area is exposed to the air more, will lose/gain heat quicker than an object with less surface area).
Potential energy and kinetic energy
