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3 years ago

Need only group b 1st question

Physics

1 answer:

galina1969 [7]3 years ago

7 0

Answer:

49 m/s

Explanation:

This is the question from the document:

1. A bag dropped from a helicopter falls with an acceleration of 9.8m/s2. What is its velocity after 5s?

We can find the answer by using the equation a = (v-u) / t

Acceleration a = 9.81m/s2

initial velocity u = 0 m/s (the bag is only dropped, so there's no initial velocity already existing)

time t= 5s

final velocity v = unknown

9.8 = (v -0) / 5

v - 0 = 9.8x5

v = 49 m/s

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Answer:

0.51 m

Explanation:

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Kinetic energy, KE=½kx²

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Potential energy, PE=mgh

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Equating KE=PE

mgh=½kx²

Making x the subject of formula

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3 years ago

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Read 2 more answers

An engine absorbs 1749 J from a hot reservoir and expels 539 J to a cold reservoir in each cycle. a. What is the engine’s effici

Masja [62]

Answer:

a)η = 69.18 %

b)W= 1210 J

c)P=3967.21 W

Explanation:

Given that

Q₁ = 1749 J

Q₂ = 539 J

From first law of thermodynamics

Q₁ = Q₂ +W

W=Work out put

Q₂=Heat rejected to the cold reservoir

Q₁ =heat absorb by hot reservoir

W= Q₁- Q₂

W= 1210 J

The efficiency given as

$\eta=\dfrac{W}{Q_1}$

$\eta=\dfrac{1210}{1749}$

$\eta=0.6918$

η = 69.18 %

We know that rate of work done is known as power

$P=\dfrac{W}{t}$

$P=\dfrac{1210}{0.305}\ W$

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