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3 years ago

Énoncez la loi de la conservation de l'energie

1 answer:

7 0

<span>la ley de la energía afirma que no puede ser ni roto o formado
</span>the law of energy states it can be neither broken or created

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A thermally isolated system is made up of a hot piece of aluminum and a cold piece of copper; the aluminum and the copper are in

blsea [12.9K]

Answer:

b) It is impossible to tell without knowing the masses.

Explanation:

The temperature change of a substance when it receives/gives off a certain amount of heat Q is given by

$\Delta T= \frac{Q}{m C_s}$

where

Q is the amount of heat

m is the mass of the substance

Cs is the specific heat capacity of the substance

In this case, we have a hot piece of aluminum in contact with a cold piece of copper: the amount of heat given off by the aluminum is equal to the amount of heat absorbed by the copper, so Q is the same for the two substances. However, we see that the temperature change of the two substances depends on two other factors: the mass, m, and the specific heat, Cs. So, since we know only the specific heat of the two substances, but not their mass, we can't tell which object will experience the greater temperature change.

4 0

3 years ago

1. True or False: Most things in motion are accelerating, few things in real life move at a constant speed.

lord [1]

1. False
2. Positive
I’m just joking I don’t know the answersss

5 0

3 years ago

Calculate the change in internal energy of the following system: A balloon is cooled by removing 0.659 kJ of heat. It shrinks on

bixtya [17]

<h2>Answer:</h2>

-310J

<h2>Explanation:</h2>

The change in internal energy (ΔE) of a system is the sum of the heat (Q) and work (W) done on or by the system. i.e

ΔE = Q + W ----------------------(i)

If heat is released by the system, Q is negative. Else it is positive.

If work is done on the system, W is positive. Else it is negative.

<em>In this case, the system is the balloon and;</em>

Q = -0.659kJ = -695J [Q is negative because heat is removed from the system(balloon)]

W = +385J [W is positive because work is done on the system (balloon)]

<em>Substitute these values into equation (i) as follows;</em>

ΔE = -695 + 385

ΔE = -310J

Therefore, the change in internal energy is -310J

<em>PS: The negative value indicates that the system(balloon) has lost energy to its surrounding, thereby making the process exothermic.</em>

<em />

5 0

3 years ago

A 91.1 kg horizontal circular platform rotates freely with no friction about its center at an initial angular velocity of 1.73 r

KIM [24]

Answer:

$\omega_f = 1.08 rad/s$

Explanation:

As we know that there is no external torque on the system of platform, banana and the monkey

so the angular momentum of the system will remains conserved

so here we can say

$L_i = L_f$

$I_o\omega = (I_o + m_1r_1^2 + m_2r_2^2)\omega_f$

here we know that

$I_o = \frac{1}{2}mR^2$

$I_o = \frac{1}{2}(91.1)(1.61)^2 = 118.1 kg m^2$

$m_1 = 9.41 kg$

$r_1 = \frac{4}{5}(1.61) = 1.29 m$

$m_2 = 21.1 kg$

Now from above equation

$118.1(1.73) = (118.1 + 9.41(1.29^2) + 21.1(1.61^2))\omega_f$

$118.1(1.73) = 188.45\omega_f$

$\omega_f = 1.08 rad/s$

8 0

3 years ago

A 1.45 kg falcon catches a 0.515 kg dove from behind in midair. What is their velocity after impact if the falcon's velocity is

True [87]

Answer:

Their velocity after the impact is 20.85 m/s.

Explanation:

Given that,

Mass of falcon, $m_1=1.45\ kg$

Mass of dove, $m_2=0.515\ kg$

Initial speed of the falcon, $u_1=26.5\ m/s$

Initial speed of the dove, $u_2=4.95\ m/s$

We need to find the final velocity after the impact. When the falcon catches the dove, it will becomes the case of inelastic collision. The conservation of momentum will be :

$m_1u_1+m_2u_2=(m_1+m_2)V\\\\V=\dfrac{m_1u_1+m_2u_2}{(m_1+m_2)}\\\\V=\dfrac{1.45\times 26.5+0.515\times 4.95}{(1.45+0.515)}\\\\V=20.85\ m/s$

So, their velocity after the impact is 20.85 m/s.

8 0

3 years ago