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2 years ago

When is work performed?

1 answer:

7 0

Answer: In summary, work is done when a force acts upon an object to cause a displacement. Three quantities must be known in order to calculate the amount of work. Those three quantities are force, displacement and the angle between the force and the displacement.

Explanation:

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Polly is pushing a box across the floor with a force of 30 N. The force of gravity is -8 in, and the normal force is eight in. W

aleksandr82 [10.1K]

Answer:

A. -30 N

Explanation:

not sure but if the box isn't moving then the force opposite of Polly would be equal to the force she's exerting.

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2 years ago

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Which of the following is a unit of rotational speed?

gladu [14]

C. Rotations per second
Or normally we'd use Radians Per second

_Brainliest if helped!!

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2 years ago

A 3-kg mass is in free fall. What is the velocity of the mass after 7 seconds??

Lisa [10]

68.6m/s is the answer

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2 years ago

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Light requires 4.5 years to travel from the nearest star to earth. If we could travel there in a spaceship going 90% of the spee

weeeeeb [17]

Answer:

Time according to earth clock (T0) = 0.22 years (Approx)

Explanation:

Given:

Time taken by light = 4.5 years

Time taken by ship = 5 years

Speed of light = c

Speed of ship (v) = 90% of c = 0.9c

Find:

Time according to earth clock (T0) = ?

Computation:

Time dilation is ,

$T(Difference) = \frac{T0}{\sqrt{1-\frac{v^2}{c^2} } }\\\\ (5-4.5)= \frac{T0}{\sqrt{1-\frac{(0.9c)^2}{c^2} } }\\\\ 0.5=\frac{T0}{\sqrt{1-0.81} }\\\\T0 =0.2179$

Time according to earth clock (T0) = 0.22 years (Approx)

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2 years ago

Jane and John Doppler effect

UkoKoshka [18]

Answer:

To summarize, Jane's star has a red light and is traveling towards the Earth while John's star has a blue light and is traveling away from the Earth. This is a prime example of the Doppler Effect in motion. The stars look different because they are traveling in different directions.

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2 years ago