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anastassius [24]

3 years ago

13

The second floor of a house is 6m above street level. How much work is reguired to lift a 300 kg refrigerator to the second stor

y?

1 answer:

zubka84 [21]3 years ago

8 0

Answer: 17.658kJ

Explanation:

The work done in lifting the refridgerator is given my

W = F.d

Where W = Work done, F = Force and d = distance/height to be covered by that force = 6m

But F = mg (this work is done against gravity)

Where m = mass of fridge and g = acceleration due to gravity.

F = 300kg × 9.81m/s^2

= 2943N

W = Fh (where h is the height to be scaled by the force)

W = 2943 × 6

W = 17658J

17.658kJ of work is needed to lift the refridgerator to a height of 6m

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A planet of mass m 6.75 x 1024 kg is orbiting in a circular path a star of mass M 2.75 x 1029 kg. The radius of the orbit is R 8

Umnica [9.8K]

Answer:

The orbital period of the planet is 387.62 days.

Explanation:

Given that,

Mass of planet $m =6.75\times10^{24}\ kg$

Mass of star $m'=2.75\times10^{29}\ kg$

Radius of the orbit $r =8.05\times10^{7}\ km$

Using centripetal and gravitational force

The centripetal force is given by

$F = \dfrac{mv^2}{r}$

$F=m\omega^2r$

We know that,

$\omega=\dfrac{2\pi}{T}$

$F=m(\dfrac{2\pi}{T})^2r$ ....(I)

The gravitational force is given by

$F = \dfrac{mm'G}{r^2}$ ....(II)

From equation (I) and (II)

$m(\dfrac{2\pi}{T})^2r=\dfrac{mm'G}{r^2}$

Where, m = mass of planet

m' = mass of star

G = gravitational constant

r = radius of the orbit

T = time period

Put the value into the formula

$T^2=\dfrac{4\pi^2R^3}{m'G}$

$T^2=\dfrac{4\times(3.14)^2\times(8.05\times10^{7})^3}{2.75\times10^{29}\times6.67\times10^{-11}}$

$T=2\times3.14\times\sqrt{\dfrac{(8.05\times10^{10})^3}{2.75\times10^{29}\times6.67\times10^{-11}}}$

$T =3.34\times10^{7}\ s$

$T= 387.62\days$

Hence, The orbital period of the planet is 387.62 days.

4 0

2 years ago

Read 2 more answers

Question 7 of 10

Lyrx [107]

Answer:

A. They can transfer energy through a vacuum

C. They vibrate in two directions that are perpendicular to each other

D. They radiate outward in all directions

Explanation:

8 0

2 years ago

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Luis rushes 40m toward his truck. He notices he forgot his shoes and returns back to his house. His total travel time is 60s.

Alenkinab [10]

Answer:

1. The average speed of Luis over the 60 s is 1.33 m/s

2. The average velocity of Luis over the 60 s is zero.

Explanation:

1. The average speed can be calculated with the following equation:

$S = \frac{d}{t}$

Where:

d: is the total distance traveled

t: is the total time = 60 s

The total distance can be calculated by the sum of the distance traveled to the truck (40 m) and the distance traveled to his home (the same 40 m), as follows:

$d = 40 m + 40 m = 80 m$

So, the average speed is:

$S = \frac{d}{t} = \frac{80 m}{60 s} = 1.33 m/s$

Hence, Luis's average speed over the 60 s is 1.33 m/s.

2. Now, the average velocity is a vector given by:

$v = \frac{\Delta x}{\Delta t} = \frac{x_{f} - x_{i}}{t}$

Where:

$x_{f}$ : is the final distance traveled (the way to his home) = 40 m

$x_{i}$ : is the initial distance traveled (the way to his truck) = 40 m

Δt: is the total time = t = 60 s

Given that Luis in his journey, returns to the same starting point (his house), the total displacement is zero, and so the average velocity is also zero:

$v = \frac{x_{f} - x_{i}}{t} = \frac{40 m - 40 m}{60 s} = 0$

Therefore, Luis's average velocity over the 60 s is zero.

I hope it helps you!

3 0

2 years ago

If a goat can slow, why can't a slow goat? (its an actual question)

Svetllana [295]

In this problem, the goat is a noun and the "slow" is acting like a verb(supposed to be an adjective but whatever...)

<span>Only objects are able "to do verbs"; That's why nouns, proper nouns, etc. are able to carry out an action. Verbs, adjectives, adverbs, etc. can't carry out actions
</span>
Example:A slug can snail but a snail can't slug
A snail can twist but a twist can't snail
Jumping can't Run and therefore, Running can't jump.

6 0

3 years ago

Roberto has twice the mass his sister Mary has (see above) but runs at the same velocity as Mary. Will his kinetic energy be twi

Lorico [155]

Answer:

one sec

Explanation:

8 0

2 years ago

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