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Leviafan [203]
4 years ago
9

The air in a room has a mass of 50kg and a specific heat of 1,000 J/(kg.C). What is the change in the thermal energy of the air

when it warms from 20 degrees C to 30 degrees C?
Physics
1 answer:
dem82 [27]4 years ago
5 0
<span>We know the change of thermal energy is proportional to the specific heat of the matter, its mass and the change of temperatures, according the following formula: Q = C*m*(Tf-Ti) where: Q is the heat added or removed (in joules, J) C is the specific heat of the matter, in our case air 1,000 J/(Kg*C) m is the mass, in our case 50 kg of air Tf is final temperature Ti is initial temperature then: Q = 1000 * 50 * (30-20) = 500,000 Joules That means that 500,000 joules need to be added to increase temperature of the room 10 ÂşC (from 20 to 30 ÂşC)</span>
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In the late 19th century, great interest was directed toward the study of electrical discharges in gases and the nature of so-ca
gizmo_the_mogwai [7]

Answer:

A) He finds the same value of q / m for different materials , B)      y = ½ (q / m) E L² / v₀ₓ² , C) v = E / B , D)   B = 2.13 10⁻⁶ T, E) For the first part I have two off-center points., For the second part I can center one point but the other is off center

Therefore the third statement is correct

Explanation:

Part A

Thomson's experiments are the first proof that the atoms that until now were considered indivisible were constituted by different elements, in these experiments Thomson himself the ratio q / m of several cathodes and always found the same value, which allowed to establish that In atoms there are two types of particles, some of which are mobile and others are still.

When examining his statements the correct one is: He finds the same value of q / m for different materials

Part B

For this part let's use Newton's second law

        F = ma

        q E = m a

        a = q / m E

We use the kinematic relationship

          y = voy t - ½ to t²

          x = v₀ₓ t

The initial vertical velocity of electrons is zero

           y = ½ a (x / v₀ₓ)²

We replace

           y = ½ (q / m) E L² / v₀ₓ²

Part C

If there is no deflection, the electric and magnetic forces are the same and in the opposite direction

         Fm = Fe

         q v B = q E

          v = E / B

Part D

       

        We replace

        y = ½ (q / m) E L² / (E / B)²

         y = ½ (q / m) L² B² / E

If we do not want any deflection the magnetic field has to return the electrons the amount that they lower y = -4.12 cm

      -4.12 10⁻² = ½ q / m 0.12² B² / 1.1 10³

       -16.97 10⁻⁴ = 6.54 10⁻³ B² q / m

      B² = -2.59 10⁻¹ q / m

      q / m = -1.758 10¹¹ C/ kg

      B = √ 0.259 1.758 10¹¹ = √ 4.55 10⁻¹²

      B = 2.13 10⁻⁶ T

Part E

As the charge that the two particles is different

For the first part I have two off-center points.

For the second part I can center one point but the other is off center

Therefore the third statement is correct

8 0
3 years ago
if a car has a kinetic energy of 400 J at 20m/s what.is the cars kinetic energy in kJ at a speed of 5 m/s
Nutka1998 [239]

Kinetic energy is an expression of the fact that a moving object can do work on anything it hits; it quantifies the amount of work the object could do as a result of its motion. It can be calculated as:

 

KE = mv^2 /2

 

We calculate the problem as follows:

 

KE = mv^2 /2

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Most grandfather clocks have pendulums with adjustable lengths. One such clock gains 10 min per day when the length of its pendu
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The length to which the pendulum will be adjusted to keep perfect time is 29.59 inches. See the explanation below.

<h3>What is the justification for the above answer?</h3>

T1 = 2πR√(L1/GM)

and

T2 = 2πR√(L1/GM)

T1/T2 = √(L1/L2).

If the pendulum has an efficient period, that means it executes with perfect frequency.

Thus,

T2 = (24 * 60)/x

= 1440/x

This means that in one day, there are perfect cycles of represented by "x". Note that there are 1440 minutes in one day.

If the other Pendulum is slower by 10 minutes, that means

T1 = 1450/x

Hence

(1450/x)/(1440/x) = √(L1/L2).

⇒ 1450/1440 = √(L1/L2).

Thus,

(1450/1440)² = 30/L

L = 30/(1450/1440)²

L = 30/(1.00694444444)²

L = 30/1.01393711419

L = 29.5876337695

L $\approx$ 29.59 inches.

Hence, the pendulum will need to be adjusted by 29.59 inches to ensure that the clock keeps perfect time.

Learn more about pendulum problems:

brainly.com/question/16617199

#SPJ4

3 0
2 years ago
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