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andrey2020 [161]

3 years ago

15

What is the change in internal energy if 20 J of heat is released from a system and the system does 50 J of work on the surround

ings?
A.-80 J
B.-20 J
C.80 J
D.20 J

2 answers:

Novay_Z [31]3 years ago

4 0

Answer:

A is the answer to this question. Hope this helps!

hjlf3 years ago

3 0

The correct answer is a -80 J

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A satellite orbits the Earth in an elliptical orbit. At perigee its distance from the center of the Earth is 22500 km and its sp

aleksley [76]

Answer:

$6.09294\times 10^{24}\ kg$

Explanation:

K = Kinetic energy

$v_p$ = Perigee speed = 4280 m/s

$v_a$ = Apogee speed = 3990 m/s

$r_p$ = Perigee Distance = 22500000 m

$r_a$ = Apogee Distance = 24100000 m

G = Gravitational constant = 6.67 × 10⁻¹¹ m³/kgs²

M = Mass of Earth

m = Mass of satellite

In this system the kinetic and potential energies are conserved

$K_p+P_p=K_a+P_a\\\Rightarrow \frac{1}{2}mv_p^2-\frac{GMm}{r_p}=\frac{1}{2}mv_a^2-\frac{GMm}{r_a}\\\Rightarrow \frac{1}{2}m(v_p^2-v_a^2)+GMm\left(\frac{1}{r_a}-\frac{1}{r_p}\right)=0\\\Rightarrow M=\frac{v_a^2-v_p^2}{2G}\times \left(\frac{1}{r_a}-\frac{1}{r_p}\right)^{-1}\\\Rightarrow M=\frac{3990^2-4280^2}{2\times 6.67\times 10^{-11}}\times \left(\frac{1}{24100000}-\frac{1}{22500000}\right)^{-1}\\\Rightarrow M=6.09294\times 10^{24}\ kg$

The mass of the Earth is $6.09294\times 10^{24}\ kg$

3 0

4 years ago

Alex is asked to move two boxes of books in contact with each other and resting on a rough floor. He decides to move them at the

Over [174]

Answer:

Part a)

$a= 0.32 m/s^2$

Part b)

$F_c = 3.6 N$

Part c)

$F_c = 5.5 N$

Explanation:

Part a)

As we know that the friction force on two boxes is given as

$F_f = \mu m_a g + \mu m_b g$

$F_f = 0.02(10.6 + 7)9.81$

$F_f = 3.45 N$

Now we know by Newton's II law

$F_{net} = ma$

so we have

$F_p - F_f = (m_a + m_b) a$

$9.1 - 3.45 = (10.6 + 7) a$

$a = \frac{5.65}{17.6}$

$a= 0.32 m/s^2$

Part b)

For block B we know that net force on it will push it forward with same acceleration so we have

$F_c - F_f = m_b a$

$F_c = \mu m_b g + m_b a$

$F_c = 0.02(7)(9.8) + 7(0.32)$

$F_c = 3.6 N$

Part c)

If Alex push from other side then also the acceleration will be same

So for box B we can say that Net force is given as

$F_p - F_f - F_c = m_b a$

$9.1 - 0.02(7)(9.8) - F_c = 7(0.32)$

$F_c = 9.1 - 0.02 (7)(9.8) - 7(0.32)$

$F_c = 5.5 N$

3 0

3 years ago

Concept map for kinetic energy, work and power

Helen [10]

Kinetic energy: the energy of motion

Work: the change in kinetic energy

Power: the rate of work done

Explanation:

The kinetic energy of an object is the energy possessed by the object due to its motion. Mathematically, it is given by:

$K=\frac{1}{2}mv^2$

where

m is the mass of the object

v is its speed

The work done an object is the amount of energy transferred; according to the energy-work theorem, it is equal to the change in kinetic energy of an object:

$W=K_f - K_i$

where

$K_f$ is the final kinetic energy

$K_i$ is the initial kinetic energy

Finally, the power is the rate of work done per unit time. Mathematically, ti can be expressed as

$P=\frac{W}{t}$

where

W is the work done

t is the time elapsed

Learn more about kinetic energy, work and power:

brainly.com/question/6536722

brainly.com/question/6763771

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brainly.com/question/7956557

#LearnwithBrainly

8 0

4 years ago

A ball of mass 2.0 kg falls vertically and hits the ground with speed 7.0 ms-1 as shown below.

Sauron [17]

Answer:

8.0 Ns

Explanation:

Change in momentum is given as:

Final momentum - Initial momentum

= m*v - m*u

Where m = mass of ball

v = final velocity

u = initial velocity

Change in momentum = (2.0 * 3.0) - (2.0 * 7.0)

= 6.0 - 14.0 = -8.0 Ns

The magnitude will be |-8.0| = 8.0 Ns

7 0

4 years ago

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The part of a circuit that increases the electric potential of the electrons is the _____. . . . . conducting wires. resistors.

Readme [11.4K]

<span>The part of a circuit that increases the electric potential of the electrons is the battery. The correct option among all the options that are given in the question is the third option or the penultimate option. I hope that this is the answer that you were looking for and the answer has actually come to your desired help.</span>

4 0

3 years ago

Read 2 more answers