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2 years ago

5

how much heat is needed to melt 2.5 kg of lead? The latent heat of fusion for lead is 5.85 Kcal/kg. The latent heat of vaporizat

ion of lead is 20.8 kcal/kg

1 answer:

sergey [27]2 years ago

5 0

I think its 550 deggres celsius.

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A 110 kg ice hockey player skates at 3.0 m/s toward a railing at the edge of the ice and then stops himself by grasping the rail

disa [49]

Answer

given,

mass of ice hockey player = 110 Kg

initial speed of the skate = 3 m/s

final speed of the skate = 0 m/s

distance of the center of mass, m = 30 cm = 0.3 m

a) Change in kinetic energy

$\Delta KE = \dfrac{1}{2}mv_f^2 - \dfrac{1}{2}mv_i^2$

$\Delta KE = \dfrac{1}{2}m(0)^2 - \dfrac{1}{2}\times 110 \times 3^2$

$\Delta KE = - 495\ J$

b) Average force must he exerted on the railing

using work energy theorem

W = Δ KE

F .d = -495

F x 0.3 = -495

F = -1650 N

the average force exerted on the railing is equal to 1650 N.

7 0

2 years ago

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A man is walking while riding a train. He says he is moving at 2 mph. A woman standing on a platform at a train station says the

Semenov [28]

The woman on the platform is correct because it is the pace of the man moving on the train not walking.

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3 years ago

Dry air is primarily composed of nitrogen. In a classroom demonstration, a physics instructor pours 3.6 L of liquid nitrogen int

neonofarm [45]

Answer:

The value is $V_n = 2.2498 \ m^3$

Explanation:

From the question we are told that

The volume of liquid nitrogen is $V_n = 3.6 \ L= 3.6 *10^{-3} \ m^3$

The density of nitrogen at gaseous form is $\rho_n = 1.2929 \ kg/m^3$ = The dry air at sea level

Generally the density of nitrogen at liquid form is

$\rho _l = 808 \ kg/m^3$

And this is mathematically represented as

$\rho_l = \frac{m}{V_l }$

=> $m = \rho_l * V_l$

Now the density of gaseous nitrogen is

$\rho_n = \frac{m}{V_n }$

=> $m = \rho_n * V_n$

Given that the mass is constant

$\rho_n * V_n = \rho_l * V_l$

$1.2929* V_n = 808 * 3.6*10^{-3}$

=> $V_n = 2.2498 \ m^3$

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2 years ago

Please answer of this question

Bogdan [553]

Answer:

$\frac{\pi }{15}$ m

Explanation:

At 10am, the minute hand and hour hand are ' 2 hours apart', since the minute hand is at 12pm and hour hand is at 10am.

Angle between the two hands = 2/12 * 360

= 60°

Arc Length = $2\pi r(\frac{60}{360} )$

= $2\pi (0.2)(\frac{1}{6} )\\= \frac{\pi }{15} m$

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2 years ago

Explain what 'vibrating' means.

drek231 [11]

Answer:

Vibrating means to move quickly to and fro.

Explanation:

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3 years ago