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Andrej [43]
3 years ago
9

When you rub a match against a rough surface, fire results, giving off light and heat. The law of conservation of energy says th

at energy cannot be created.
How can you explain the fire seeming to come from nowhere?

The energy was stored in chemical bonds before it became heat and light.
Matches are made to take up energy from surfaces.
The energy started out as the sound energy of the rubbing match.
Physics
2 answers:
Trava [24]3 years ago
7 0
The law of conservation of energy states that energy can neither be created nor destroyed. striking a match stick with a surface that conducts heat, it is not part of the law
shutvik [7]3 years ago
4 0
The energy was stored in chemical bonds before it became heat and light, it is the result when you rub a match against a rough surface. Energy can not be created nor destroyed but it can be stored, potential energy is stored in a match when you strike it, it releases that energy.
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A train travels from the bottom of a hill to the top of a hill, its moves slower by the time it reaches the top is an example of
Neko [114]
The answer is letter C. <span>A train travels from the bottom of a hill to the top of a hill, its moves slower by the time it reaches the top is an example of negative acceleration.

In physics, acceleration can be described as an objects change of velocity. When an object gains velocity, it is positive acceleration, and negative acceleration for the opposite.

</span>

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5 0
3 years ago
Read 2 more answers
an object weighting 100g is thrown upwards from the ground at a speed of 100 m/s.where will the potential energy of the object b
Kay [80]

Answer:

333.3 m

Explanation:

Given

m =100g\ =\  0.1kg\\v = 100 m/s\\g = 10 m/s ^2

Potential energy =\frac{2}{3}\  of\  Kinetic\  energy......Equation(1)

We know that

Potential energy=mgh

Kinetic energy =\frac{1}{2} mv^{2}

Now From the Equation(1)

mgh=\frac{2}{3}*\frac{1}{2} mv^{2}\\  gh=\frac{v^{2} }{3} \\10 * h=\ \frac{10000}{3}\\ h=\ \frac{1000}{3} \\h=333.3\  m

3 0
3 years ago
How are energy and mass connected during the formation of an atom? Energy is absorbed, so the mass is increased. Energy is relea
zloy xaker [14]

Answer:

Energy is absorbed, so the mass is reduced.

Explanation:

The relationship between the mass and the energy is given by Einstein formula as :

E=mc^2

m is the mass of an atom

c is the speed of light

When an atom is formed, the energy gets absorbed. As a result mass will decrease as per Einstein's equation. So, the correct option is (c) "Energy is absorbed, so the mass is reduced".

4 0
3 years ago
Read 2 more answers
Which element could provide one atom to make an ionic bond with nitrogen?​
aev [14]

Answer:

boron

aluminum

gallium

indium

thallium

Explanation:

Any of these could work. Nitrogen has 5 valence electrons so you just needed to pick an element that has 3 valence electrons that nitrogen could borrow. This periodic table shows valence electron counts:

8 0
3 years ago
A 15 kg bucket of water is suspended by a very light ropewrapped around a solid uniform cylinder 0.300 m in diamter withmass 12.
matrenka [14]

Answer:

Part a)

T = 42 N

Part b)

v_f = 11.8 m/s

Part c)

t = 1.7 s

Part d)

F = 159.7 N

Explanation:

Part a)

While bucket is falling downwards we have force equation of the bucket given as

mg - T = ma

for uniform cylinder we will have

TR = I\alpha

so we have

T = \frac{1}{2}MR^2(\frac{a}{R^2})

T = \frac{1}{2}Ma

now we have

mg = (\frac{M}{2} + m)a

a = \frac{mg}{(\frac{M}{2} + m)}

a = \frac{15 \times 9.81}{(6 + 15)}

a = 7 m/s^2

now we have

T = \frac{12 \times 7}{2}

T = 42 N

Part b)

speed of the bucket can be found using kinematics

so we have

v_f^2 - v_i^2 = 2 a d

v_f^2 - 0 = 2(7)(10)

v_f = 11.8 m/s

Part c)

now in order to find the time of fall we can use another equation

v_f - v_i = at

11.8 - 0 = 7 t

t = 1.7 s

Part d)

as we know that cylinder is at rest and not moving downwards

so here we can use force balance

F = T + Mg

F = 42 + (12 \times 9.81)

F = 159.7 N

5 0
3 years ago
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