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xeze [42]
3 years ago
12

1. If a system is isolated, the total energy within that system is constant. Consider the case of a hot cup of coffee: when it c

ools down, the energy goes into the surrounding air, causing the air to warm. If the coffee and the air are placed in an isolated chamber, the total energy of the system (coffee + air) is constant because the energy lost by the coffee is exactly equal to the energy gained by the air.
The only way for the total energy of a system to change is when it is not isolated, meaning that external forces or sources of energy interact with the system. If we want to define a system where the total energy is conserved, which one of the choices below would be the best system to consider?
A. The person
B. The person and the Earth
C. The Earth
2. Based on your answer to Question 1, why doesn’t the total energy of the Earth-person system change when the person goes up to a new height, gaining potential energy?
Physics
1 answer:
nignag [31]3 years ago
6 0

Answer:

1. B. The person and the Earth

2. This is because the energy gained by the person equals the energy lost by the earth,

Explanation:

1.

B. The person and the Earth

This is because the person and the earth both represent a system. A system consists of more than one item. A system consists of two or more items interacting with each other.

2. This is because, the energy of an isolated system is conserved according to the second law of thermodynamics which states that in an isolated system, energy can neither be created nor destroyed. So, there is an exchange of energy between the person and the Earth. So, the energy gained by the person at the new height equals the energy lost by the earth. And thus, the total energy of the system remains constant.

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There is strong evidence that Europa, a satellite of Jupiter, has a liquid ocean beneath its icy surface. Many scientists think
dangina [55]

Answer:

4.44 rpm

Explanation:

\omega = Angular speed

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

r = Radius of Europa = \frac{3138000}{2}\ m

R = Radius of arm = 6 m

The acceleration due to gravity is given by

g=\frac{GM}{r^2}\\\Rightarrow g=\frac{6.67\times 10^{-11}\times 4.8\times 10^{22}}{\left(\frac{3138000}{2}\right)^2}\\\Rightarrow g=1.3\ m/s^2

Here the centripetal acceleration of the arm and acceleration due to gravity are equal

a_c=\omega^2R

a_c=g\\\Rightarrow \omega^2R=1.3\\\Rightarrow \omega^2\times 6=1.3\\\Rightarrow \omega=\sqrt{\frac{1.3}{6}}\\\Rightarrow \omega=0.46547\ rad/s

Converting to rpm

1\ rad/s=\frac{60}{2\pi}\ rpm

0.46547\ rad/s=0.46547\times \frac{60}{2\pi}\ rpm=4.44\ rpm

The angular speed of the arm is 4.44 rpm

8 0
3 years ago
You and a friend each carry identical boxes from the first floor of a building to a room located on the second floor, farther do
melamori03 [73]

Answer:

Work done in both the cases will be same

Explanation:

As we know that the work done against gravity is given as

W = F_g .d

here we know that gravitational force is a conservative force and the work done against gravitational force is independent of the path

So here the work done by person to move the object between two different heights will be independent of the path they choose

So for the first person and second person will be same in both the cases because the height through which the boxes are transferred will be same in both the cases

8 0
3 years ago
Mars had a mass of 6.38* 10^23 kg and a radius of 3,390,000meter what is the force of gravity experienced by a mars rover with a
d1i1m1o1n [39]

I hope its helps you . you can also write 1.44×10^3 it will be better

7 0
1 year ago
Which of the following has the most momentum?
IrinaK [193]

Answer:you riding your bike at 12m/s

Explanation: this is because momentum P = mass x velocity. With a bigger mass and a velocity of about 12m/s, you really have a great momentum.

6 0
3 years ago
A car is traveling with 90km/hr and another car with 20m/s in opposite direction. Calculate the relative velocity.
Slav-nsk [51]
90 km/h is 25 m/s
the relative velocity when cars are traveling in opposite directions is the sum of the two
25+20= 45 m/s
5 0
3 years ago
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