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bija089 [108]
3 years ago
15

How much work must be done in the car to slow it from 100km/h to 50km/h

Physics
1 answer:
Brilliant_brown [7]3 years ago
7 0

Answer:

-96.465m joule

Explanation:

Let m = mass of the car and v1 = initial velocity and v2 = final velocity

Given.

Initial velocity = 100 km/h

final velocity = 50 km/h

What is work done in the car to slow it from 100km/h to 50km/h?

v1=100km/h=27.78m/s

v2=50km/h=13.89m/s

The work done in the car to slow it from v1 to v2.

w=Δk

w=k2-k1

w= \frac{1}{2}m(v2)^{2}- \frac{1}{2}m(v1)^{2}

w=\frac{1}{2} m(v2-v1)^{2}

w=\frac{1}{2}\times m(13.89 -27.78)^{2}

w=\frac{1}{2}\times m(-13.89)^{2}

w=\frac{1}{2}\times m\times (-192.93)

w=-96.465m joule.

Therefore, the work done is -96.465m joule

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Shalnov [3]

Answer:

the closest distance that she can see an object clearly when she wears her contacts is 22.2 cm

Explanation:

Given the data in the question,

near point = 20 cm

far point = 2 m = 200 cm

Now, for an object that is infinitely far away, the image is at is its far point.

so using the following expression, we can determine the focal length

1/f = 1/i + 1/o

where f is the focal length, i is the image distance and o is the object distance.

here, far point i = 2 m = 200 cm  and v is ∞

so we substitute

1/f = 1/(-200 cm)  +  1/∞

f = -200 cm

Also, for object at its closest point, the image appear at near point,

so

1/f = 1/i + 1/o

we make o the subject of formula

o = ( i × f ) / ( i - f )

given that near point i = 20 cm

we substitute

o = ( -20 × -200 ) / ( -20 - (-200) )

o = 4000 / 180

o = 22.2 cm

Therefore, the closest distance that she can see an object clearly when she wears her contacts is 22.2 cm

4 0
3 years ago
One mole of ideal gas is slowly compressed to one-third of its original volume. in this compression, the work done on the gas ha
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A boiling pot of water (the water travels in a current throughout the pot), a hot air balloon (hot air rises, making the balloon rise) , and cup of a steaming, hot liquid (hot air rises, creating steam) are all situations where convection occurs. 
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4 0
3 years ago
A plane stops from 250 mph in 25 seconds. Calculate the plane's acceleration.
Lelechka [254]

Explanation:

Given:

v₀ = 250 mph

v = 0 mph

t = 25 s

Find: a

v = at + v₀

(0 mph) = a (25 s) + (250 mph)

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3 years ago
In designing circular rides for amusement parks, mechanical engineers must consider how small variations in certain parameters c
Bess [88]

Answer:

Part a)

dF = -\frac{mv^2}{r^2} dr

Part b)

dF = \frac{2mvdv}{r}

Part c)

dT = - \frac{2\pi r}{v^2} dv

Explanation:

Part a)

As we know that force on the passenger while moving in circle is given as

F = \frac{mv^2}{r}

now variation in force is given as

dF = -\frac{mv^2}{r^2} dr

here speed is constant

Part b)

Now if the variation in force is required such that r is constant then we will have

F = \frac{mv^2}{r}

so we have

dF = \frac{2mvdv}{r}

Part c)

As we know that time period of the circular motion is given as

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so here if radius is constant then variation in time period is given as

dT = - \frac{2\pi r}{v^2} dv

8 0
3 years ago
A shell of mass m and speed v explodes into two identical fragments. If the shell was moving horizontally (the positive x direct
-Dominant- [34]

Answer:

The velocity of the other fragment immediately following the explosion is v .

Explanation:

Given :

Mass of original shell , m .

Velocity of shell , + v .

Now , the particle explodes into two half parts , i.e  \dfrac{m}{2} .

Since , no eternal force is applied in the particle .

Therefore , its momentum will be conserved .

So , Final momentum = Initial momentum

mv=\dfrac{mv}{2}+\dfrac{mu}{2}\\\\u=v

The velocity of the other fragment immediately following the explosion is v .

4 0
3 years ago
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