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3 years ago

NEED HELP ASAP!! Will give Brainliest.

Physics

1 answer:

olga2289 [7]3 years ago

5 0

a. 25 joules of work is done by the object.

Explanation:

According to the work-energy theorem, the work done ON an object is equal to the change in kinetic energy of the object, therefore:

$W=K_f -K_i= \frac{1}{2}mv^2-\frac{1}{2}mu^2$

where

$K_f = \frac{1}{2}mv^2$ is the final kinetic energy of the car, with

m = 2 kg being the mass of the car

v = 0 is the final speed of the car (brought to rest)

$K_i = \frac{1}{2}mu^2$ is the initial kinetic energy of the car, with

u = 5 m/s being the initial speed of the car

Substituting numbers, we find:

$W=\frac{1}{2}(2)(0)^2 - \frac{1}{2}(2)(5)^2=-25 J$

The negative sign means that the work done ON the car is negative: this means therefore that the work has been actually done BY the car. In fact, the car has lost its kinetic energy: this means that it has done work on the surrounding, converting its kinetic energy into other forms of energy.

Learn more about work and kinetic energy:

brainly.com/question/6763771

brainly.com/question/6443626

brainly.com/question/6536722

#LearnwithBrainly

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Calculate the Latent Heat of Vaporization. (Please see picture attached)

Hunter-Best [27]

Answer:

20 J/g

Explanation:

In this question, we are required to determine the latent heat of vaporization

To answer the question, we need to ask ourselves the questions:

What is latent heat of vaporization?

It is the amount of heat required to change a substance from its liquid state to gaseous state without change in temperature.

It is the amount of heat absorbed by a substance as it boils.

How do we calculate the latent heat of vaporization?

Latent heat is calculated by dividing the amount of heat absorbed by the mass of the substance.

In this case;

Mass of the substance = 20 g
Heat absorbed as the substance boils is 400 J (1000 J - 600 J)

Thus,

Latent heat of vaporization = Quantity of Heat ÷ Mass

= 400 Joules ÷ 20 g

= 20 J/g

Thus, the latent heat of vaporization is 20 J/g

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3 years ago

Describe the energy change in the particles of a substance during melting. A) The kinetic energy of the particles remains unchan

Rina8888 [55]

Answer:

As ice melts into water, kinetic energy is being added to the particles. This causes them to be 'excited' and they break the bonds that hold them together as a solid, resulting in a change of state: solid -> liquid.

Explanation:

As we may know, the change in state of an object is due to the change in the average kinetic energy of the particles.

This average kinetic energy is proportional to the temperature of the particles.

This is because heat is a form of energy; by adding energy to ice - heat, you "excite" the water molecules, breaking the interactions in the lattice structure and forming weaker, looser hydrogen-bonding interactions.

This causes the ice to melt. This is demonstrated in the image below.

More generally, when you remove energy - the object cools down, the particles move a lot slower. So slow, that they individually attract other molecules more than before, and this results in a physical change that also changes the state.

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2 years ago

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