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pav-90 [236]
2 years ago
13

calculate the work done in kilo joules in lifting a mass of 20kg at steady velocity through a vertical height of 20m

Physics
1 answer:
bulgar [2K]2 years ago
5 0

Answer:

\huge\boxed{\sf Work\ done = 4 kJ}

Explanation:

Since work done is in the form of potential energy, we will use the formula of potential energy here.

We know that,

<h3>P.E. = mgh </h3>

Where,

m = mass = 20 kg

g = acceleration due to gravity = 10 m/s²

h = vertical height = 20 m

So,

<h3>Work done = mgh</h3>

Work done = (20)(10)(20)

Work done = 4000 joules

Work done = 4 kJ

\rule[225]{225}{2}

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A meter stick is held vertically with one end on the floor and is then allowed to fall. Find the speed of the other end when it
Tems11 [23]

Answer:

5.4 ms⁻¹

Explanation:

Here we have to use conservation of energy. Initially when the stick is held vertical, its center of mass is at some height above the ground, hence the stick has some gravitational potential energy. As the stick is allowed to fall, its rotates about one. gravitational potential energy of the stick gets converted into rotational kinetic energy.

L = length of the meter stick = 1 m

m = mass of the meter stick

w = angular speed of the meter stick as it hits the floor

v = speed of the other end of the stick

we know that, linear speed and angular speed are related as

v = r w\\w = \frac{v}{r}

h = height of center of mass of meter stick above the floor = \frac{L}{2} = \frac{1}{2} = 0.5 m

I = Moment of inertia of the stick about one end

For a stick, momentof inertia about one end has the formula as

I = \frac{mL^{2} }{3}

Using conservation of energy

Rotational kinetic energy of the stick = gravitational potential energy

(0.5) I w^{2} = mgh\\(0.5)(\frac{mL^{2} }{3}) (\frac{v}{L} )^{2} = mgh\\(0.5)(\frac{v^{2} }{3}) = gh\\(0.5)(\frac{v^{2} }{3}) = (9.8)(0.5)\\v = 5.4 ms^{-1}

7 0
3 years ago
How is the Maunder minimum related to climate?
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Maunder minimum is related to climate due to the unusually low sunspot activity correlates to unusually cold climatic events. The answer is letter A. It happened around 1645 and 1715 and also coincided with the phenomena ‘Little Ice Age’ (1500 – 1850) in the Northern Hemisphere.

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3 years ago
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A small boy is playing with a ball on a stationary train. If he places the ball on the floor of the train, when the train starts
expeople1 [14]

A small boy is playing with a ball on a stationary train. If he places the ball on the floor of the train, when the train starts moving the ball moves toward the back of the train. This happened due to inertia

An object at rest remains at rest, or if in motion, remains in motion unless a net external force acts on it .  

When a train starts moving forward, the ball placed on the floor  tends to fall backward is an example of inertia of rest. Due to the reason that the lower part of the ball is in contact with the surface and rest of the part is not . As the train starts moving, its lower part gets the motion as the floor starts moving but the upper part will remain as it is as it is not in contact with the floor , hence do not attain any motion due to the inertia of rest simultaneously i.e. it tends to remain at the same place.

To learn more about inertia here :

brainly.com/question/11049261

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8 0
1 year ago
A filled water tower sits on the top of the highest hill near a city. The cylindrical tower has a height of 55.0 m
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Answer:

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Explanation:

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P = ρgh

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P = (1000 kg/m³) (9.8 m/s²) (55.0 m)

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Physics approach to study macromoelcues at nanoscales <br> in detail plx
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Answer:

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