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4 years ago

HELP!! I WILL MARK BRAINLY!

Physics

2 answers:

Snezhnost [94]4 years ago

8 0

Answer:

A chemical change produces a new substance, while a physical change does not

Genrish500 [490]4 years ago

6 0

In a nutshell, a chemical change produces a new substance, while a physical change does not. A material may change shapes or forms while undergoing a physical change, but no chemical reactions occur and no new compounds are produced.

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Thinking about the winter we missed out on this year. Calvin and his tiger go sledding down a snowy hill. There is friction betw

jarptica [38.1K]

Answer:

a) W=0, b) Work is negative, c) work is positive and scientific energy variation is positive, d) the variation of the potential enrgy is negative,

e) total work is positive

Explanation:

Work in physics is defined by the scalar scalar product of force by displacement

W = F. dx

The bold are vectors; this can be written in the form of the mules of the quantities

W = F dx cos θ

where θ is the angle between force and displacement.

a) The normal force is perpendicular to the inclined plane which is perpendicular to the displacement, therefore the angle is

θ = 90 cos 90 = 0

W=0

In conclusion the work is zero

b) The friction force opposes the displacement whereby the angle is

θ = 180 cos 190 = -1

W = - fr d

Work is negative

c) To calculate the change in kinetic energy we use that the work is equal to the variation of the kinetic energy

m g sin θ L = ΔK

this magnitude is positive since the angle is zero cos 0 = 1

how the system starts from rest ΔK = Kf -K₀= + Kf -0

work is positive and scientific energy variation is positive

d) change in potential energy

The potential energy is is ΔU = Uf -U₀

we fix the reference system in the bases of the plane so Uf = 0

ΔU = -U₀

the variation of the potential enrgy is negative

e) The total work is formed by the work of the weight component, the work of the friction force

W_Total = W_weight - W_roce

as the body moves down

W_Total> 0

Therefore the total work is positive

3 0

3 years ago

The half-life of a certain radioactive substance is 12 hours. There are 19 grams present initially. a. Express the amount of su

neonofarm [45]

Answer:

(a) $N=19\times e^{-\lambda t}$

(b) 15 hours

Explanation:

half life, T = 12 hours

No = 19 g

(a) Let N be the amount remaining after time t.

Let λ be the decay constant.

$\lambda =\frac {0.6931}{T}$

The equation of radioactivity used here is given by

$N=N_{o}e^{-\lambda t}$

$N=19\times e^{-\lambda t}$

(b) N = 8 gram

Substitute the values in above equation

$\lambda =\frac {0.6931}{12}$

λ = 0.0577 per hour

So, $8=19\times e^{-0.577t}$

$e^{-0.0577t}=0.421$

Take natural log on both the sides

- 0.0577 t = - 0.865

t = 15 hours

4 0

3 years ago

a student solving for the acceleration of an object has applied appropriate physics principles and obtained the expression a

kozerog [31]

Given:

$Force, f = 12 \frac{kg-m}{sec^{2} }$

$Mass, m = 7 kg$

$Acceleration, a_{1} = 3\;\frac{m}{sec^{2} }$

$a = a_{1}+\frac{f}{m}$

$Substitute\;the\;values\;of\;f,\;m\;and\;a_{1}\;in\;the\;above\;equation,$

$a = 3+\frac{12}{7}$

$a = 3 + 1.714$

Therefore, the acceleration is,

$a = 4.714\;\frac{m}{sec^{2} }$

<h3>Explain Acceleration?</h3>

An object's rate of changing its velocity is known as its acceleration, which is a vector quantity. If an object's velocity is changing, it is accelerating. When anything moves faster or slower in a straight line, it is said to have been accelerated. Even if the speed is constant, motion on a circle accelerates because the direction is always shifting.

To learn more about Acceleration, visit:

brainly.com/question/12550364

#SPJ4

3 0

1 year ago

"In this lesson, you learned about renewable energy resources and nonrenewable energy resources. Think about the resources discu

Nutka1998 [239]

U can also add solar energy and hydro energy. Solar energy is by using the sun, while hydro is by using the force of water.
This is how hydro energy works:
its is usually built near a waterfall, OK so when the water falls of the cliff of the water fall , it creates a force which helps turn the generator and then it is carried into poles of electricity.
Hope this helps plus i gave u extra point Good luck :)

5 0

3 years ago

1. Which direction will the box move in the diagram below? (1 point)

svetoff [14.1K]

I think it would'nt move at all but im not postive

6 0

4 years ago