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alekssr [168]
3 years ago
9

How much work does a bricklayer do to carry 30.2 kg of bricks from the ground up to the third floor (height = 11.1 m) of a build

ing under construction? What is the gravitational potential energy of the brick-Earth system when the bricklayer reaches the third floor?
Physics
1 answer:
Julli [10]3 years ago
7 0

Answer:

Work done by the bricklayer, W = 3.285 kJ

Therefore, the gravitational potential energy of the brick-Earth system =  3.285 kJ

Explanation:

Work done is the product of applied force and distance moved by the force.

The force on an object in the gravitational field is equal to the product of the mass of the object and acceleration due to gravity This force is the weight of the object or body. In lifting an object from a lower height to a higher one, the distance moved is equal to the increase in height.

Work done in lifting an object in a gravitational field = mgh

where m = mass of the object, g = acceleration due to gravity, h = height

From the question, m = 30.2 kg, g = 9.8 m/s², h = 11.1 m

Work done by the bricklayer = 30.2 * 9.8 * 11.1 = 3285.156 J

Work done by the bricklayer, W = 3.285 kJ

Gravitational Potential Energy, PEg = mgh = W

Therefore, the gravitational potential energy of the brick-Earth system =  3.285 kJ

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Explanation:

Given that,

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If v is the image distance from the lens, we can find it using lens formula as follows :

\dfrac{1}{v}-\dfrac{1}{u}=\dfrac{1}{f}\\\\\dfrac{1}{v}=\dfrac{1}{f}+\dfrac{1}{u}\\\\\dfrac{1}{v}=\dfrac{1}{0.14 }+\dfrac{1}{(-0.21)}\\\\v=0.42\ m

(a) Magnification,

m=\dfrac{v}{u}\\\\m=\dfrac{0.42}{(-0.21)}\\\\m=-2

(b) Magnification, m=\dfrac{h'}{h}

h' is image height

-2=\dfrac{h'}{0.066}\\\\h'=-2\times 0.066\\\\h'=-0.132\ m

Hence, this is the required solution.

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Answer:

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In a longitudinal wave, the particles vibrate at right angles in reference to the wave motion.

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