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2 years ago

Calculate the power of a person that does 8kJ of work in 4 hours

Physics

2 answers:

telo118 [61]2 years ago

7 0

Answer:

Explanation:

Energy used is power multiplied by time.

Power is energy used divided by time

8 kj is 8000 j

4 hours is 240 minutes

240 minutes is 14400 seconds

8000j divided by 14400 is 0.55 recurring, measured in watts

anzhelika [568]2 years ago

3 0

$\text{Power,}~ P = \dfrac{\text{Work done}}{\text{Time}}\\\\\\~~~~~~~~~~~~~=\dfrac{8 \times 1000~J}{4 \times 3600~ s}\\\\\\~~~~~~~~~~~~~~=\dfrac{80}{144}\\\\\\~~~~~~~~~~~~~~=0.56~ W$

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You throw a ball upward with a speed of 14m/s. What is the acceleration of the ball after it leaves your hand? Ignore air resist

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A ball with a mass of 275 g is dropped from rest, hits the floor and rebounds upward. If the ball hits the floor with a speed of

Alla [95]

Answer:

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Explanation:

It is given that,

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It rebounds with a speed of 1.7 m/s i.e. v = 1.7 m/s (+ve because the ball rebounds in upward direction)

We have to find the change in the ball's momentum. It is given by :

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$\Delta p=m(v-u)$

$\Delta p=0.275\ kg(1.7\ m/s-(-2.4\ m/s))$

$\Delta p=1.1275\ kg-m/s$

So, the change in the momentum is 1.1275 kg-m/s

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