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2 years ago

At a fabrication plant, a hot metal forging has a mass of 75 kg and a specific heat

Physics

1 answer:

Lesechka [4]2 years ago

3 0

Answer:

940°C

Explanation:

Heat lost by the forging = heat gained by the oil

-mCΔT = mCΔT

-(75 kg) (430 J/kg/°C) (47°C − T) = (710 kg) (2700 J/kg/°C) (47°C − 32°C)

-32250 (47°C − T) = 1917000 (15°C)

47°C − T = -892°C

T = 939°C

Rounded to two significant figures, the initial temperature is 940°C.

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In February 1955, a paratrooper fell 370 m from an airplane without being able to open his chute but happened to land in snow, s

nevsk [136]

a) 0.94 m

The work done by the snow to decelerate the paratrooper is equal to the change in kinetic energy of the man:

$W=\Delta K\\-F d = \frac{1}{2}mv^2 - \frac{1}{2}mu^2$

where:

$F=1.1 \cdot 10^5 N$ is the force applied by the snow

d is the displacement of the man in the snow, so it is the depth of the snow that stopped him

m = 68 kg is the man's mass

v = 0 is the final speed of the man

u = 55 m/s is the initial speed of the man (when it touches the ground)

and where the negative sign in the work is due to the fact that the force exerted by the snow on the man (upward) is opposite to the displacement of the man (downward)

Solving the equation for d, we find:

$d=\frac{1}{2F}mu^2 = \frac{(68 kg)(55 m/s)^2}{2(1.1\cdot 10^5 N)}=0.94 m$

b) -3740 kg m/s

The magnitude of the impulse exerted by the snow on the man is equal to the variation of momentum of the man:

$I=\Delta p = m \Delta v$

where

m = 68 kg is the mass of the man

$\Delta v = 0-55 m/s = -55 m/s$ is the change in velocity of the man

Substituting,

$I=(68 kg)(-55 m/s)=-3740 kg m/s$

7 0

2 years ago

Calculate the speed for a car that went a distance of 125 meters in 2 seconds time.

stiv31 [10]

Answer:

Explanation:

The speed of the car can be found by using the formula

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

d is the distance

t is the time

From the question we have

$s = \frac{125}{2} = 62.5 \\$

We have the final answer as

Hope this helps you

5 0

1 year ago

A wave is moving at 18 m/s. If its wavelength is 3 meters, what is its frequency?

Vlada [557]

here's the solution,

we know that,

=》

$wave \: speed = wavelength \times frequency$

so,

=》

$18 = 3 \times f$

=》

$f = \dfrac{18}{3}$

=》

$f = 6$

frequency = 6 hertz

7 0

2 years ago

The radius of Earth is . The average Earth-Sun distance is . How many Earths would fit between Earth and the Sun if they are sep

Verdich [7]

Answer:

The radius of the earth is 6,371 km.

The average Earth-Sun distance is 152.09 million km

How many Earths would fit between Earth and the Sun if they are separated by their average distance? Approximately 11,936 Earths.

I didn't really understand the last part, but if you don't get a better answer please mark me as brainliest.

6 0

2 years ago

A capacitor consists of two square plates, 8.7 cm on a side, separated by a 2.0 mm air gap. How much energy would be stored in t

slavikrds [6]

Answer:

122.84 J

Explanation:

Since plate is square, area, A is given by $(8.7/100)^{2}=0.007569m^{2}$

The distance between plates, d, is given in the question as 2mm=0.002m

Charge on plate, Q, as given in the question is 240 $\mu c$

Assuming mica dielectric constant, k of 7

Capacitance, C is given by

C= $\frac {k\epsilon_{o}A}{d}=\frac {(7)(8.85*10^{-12})(0.007569)}{0.002}=2.34*10*^{-10}F$

Stored energy, E is given by

E= $\frac {Q^{2}}{2C}=\frac {(240*10^{-6})^{2}}{2*(2.34*10^{-10})}=122.84J$

Therefore, the stored energy is 122.84 J

5 0

2 years ago