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3 years ago

13

How much thermal energy must be added to a 1.4 kg piece of lead to convert it from a solid to a liquid at 327.5∘? Latent heat of

fusion for lead is Lf=2.32×104J/kg.

1 answer:

AleksAgata [21]3 years ago

5 0

Answer:

energy is equal to mass times latent heat.

so, E = 1.4×2.32×10^4=44800 j

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Martin has severe myopia, with a far point on only 17 cm. He wants to get glasses that he'll wear while using his computer whose

marusya05 [52]

Answer:

Explanation:

Far point = 17 cm . That means he can not see beyond this distance .

He wants to see at an object at 65 cm away . That means object placed at 65 has image at 17 cm by concave lens . Using lens formula

1 / v - 1 / u = 1 / f

1 / - 17 - 1 / - 65 = 1 / f

= 1 / 65 - 1 / 17

= - .0434 = 1 / f

power = - 100 / f

= - 100 x .0434

= - 4.34 D .

6 0

3 years ago

12. A frain moves from rest to a speed of 25 m/s in 30.0 seconds. What is its acceleration?

ziro4ka [17]

initial velocity=u=0m/s
Final velocity=v=25m/s
Time=t=30s

$\\ \tt\longmapsto Acceleration=\dfrac{v-u}{t}$

$\\ \tt\longmapsto Acceleration=\dfrac{25-0}{30}$

$\\ \tt\longmapsto Acceleration=\dfrac{25}{30}$

$\\ \tt\longmapsto Acceleration=0.8m/s^2$

6 0

3 years ago

J.J. Thomson discovered the electron by noticing that: A. molecules with the same atoms exhibited the same chemical properties.

GenaCL600 [577]

J.J. Thomson discovered the electron by noticing that a beam of particles could be influenced by an electric or magnetic force.. That is option B.

<h3>What is an electron?</h3>

An electron can be defined as the part of an atom that is negatively charged and is found revolving round the nucleus of an atom.

J.J. Thomson was the scientist that discovered electrons through subjecting two oppositely-charged electric plates around the cathode ray.

He noticed that the particles where deflected by both the magnetic and electric fields.

Learn more about cathode rays here:

brainly.com/question/4441361

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4 0

2 years ago

In classical physics, consider a 2 kg block hanging on a spring with a spring constant of 50 N/m. Ignore air resistance. The blo

RUDIKE [14]

Answer:

v = 0

Explanation:

This problem can be solved by taking into account:

- The equation for the calculation of the period in a spring-masss system

$T = \sqrt{\frac{m}{k} }$ ( 1 )

- The equation for the velocity of a simple harmonic motion

$x = \frac{2\pi }{T}Asin(\frac{2\pi }{T}t)$ ( 2 )

where m is the mass of the block, k is the spring constant, A is the amplitude (in this case A = 14 cm) and v is the velocity of the block

Hence

$T = \sqrt{\frac{2 kg}{50 N/m}} = 0.2 s$

and by reeplacing it in ( 2 ):

$v = \frac{2\pi }{0.2s}(14cm)sin(\frac{2\pi }{0.2s}(0.9s)) = 140\pi sin(9\pi ) = 0$

In this case for 0.9 s the velocity is zero, that is, the block is in a position with the max displacement from the equilibrium.

5 0

3 years ago

An object in static equilibrium has a coefficient of static friction as 0.110. If the normal force acting on the object is 95.0

igomit [66]

Answer:

mass = 9.7 kg

Explanation:

As we know that when object is at rest on the ground of flat base then we will have

$N - mg = 0$

so from here

$N = mg$

now we have

N = 95 Newton

now from above equation we will have

$95 = m\times g$

$95 = m\times 9.8$

$m = 9.7 kg$

7 0

3 years ago