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3 years ago

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Classify each of the following as an observation, a law, or a theory. (a) All matter is made of tiny, indestructible particles c

alled atoms. (b) When iron rusts in a closed container, the mass of the container and its contents does not change. (c) In chemical reactions, matter is neither created nor destroyed. (d) When a match burns, heat is evolved.

1 answer:

jenyasd209 [6]3 years ago

5 0

Answer: a) Theory

Explanation: “Dalton’s Atomic Theory”

b) When iron rusts in a container... is an Observation

c) The “Law”of Conservation of Mass

d) is an observation

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A 1500-kg car traveling east with a speed of 25.0 m/s collides at an intersection with a 2500-kg van traveling north at a speed

IgorC [24]

Answer:

The direction and magnitude of velocity is 38.65° and 12.005 m/s

Explanation:

Given that,

Mass of car = 1500 kg

Speed of car = 25.0 m/s

Mass of van = 2500 kg

Speed of van =20.0 m/s

We need to calculate the velocity

Using conservation of energy

$m_{c}u_{i}+m_{v}u_{i}=(m_{c}+m_{v})v_{f}$

$1500(25i+0j)+2500(0+20j)=4000(v_{f})$

$v_{f}=\dfrac{1500\times25}{4000}i+\dfrac{1500\times20}{4000}j$

$v_{f}=9.375 i+7.5 j$

The magnitude of velocity

$|v_{f}|=\sqrt{(9.375)^2+(7.5)^2}$

$|v_{f}|=12.005\ m/s$

We need to calculate the direction

$\tan\theta=\dfrac{coefficient\ of\ j}{coefficient\ of\ i}$

$\tan\theta=\dfrac{7.5}{9.375}$

$\theta=\tan^{-1}0.8$

$\theta=38.65^{\circ}$

Hence, The direction and magnitude of velocity is 38.65° and 12.005 m/s.

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4 years ago

Calculate the correct fuse that should be used for a 230V,1KW electric hair dryer.

zzz [600]

Answer: 4 A

Explanation:

Given

Voltage $V=230\ V$

Power $P=1\ kW$

Power is given by $P=VI\\$

Insert the values

$\Rightarrow 1000=230\times I\\\\\Rightarrow I=\dfrac{1000}{230}\\\\\Rightarrow I=3.84\ A$

The rating of fuse is slightly higher than the normal operating conditions. Therefore, a 4 A fuse should be used here.

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3 years ago

The masses of the earth and moon are 5.98 x 1024 and 7.35 x 1022 kg, respectively. Identical amounts of charge are placed on eac

dybincka [34]

Answer:

The magnitude of charge on each is $5.707\times 10^{13} C$

Solution:

As per the question:

Mass of Earth, $M_{E} = 5.98\times 10^{24} kg$

Mass of Moon, $M_{M} = 7.35\times 10^{22} kg$

Now,

The gravitational force of attraction between the earth and the moon, if 'd' be the separation distance between them is:

$F_{G} = \frac{GM_{E}M_{M}}{d^{2}}$ (1)

Now,

If an identical charge 'Q' be placed on each, then the Electro static repulsive force is given by:

$F_{E} = \frac{1}{4\pi\epsilon_{o}}\frac{Q^{2}}{d^{2}}$ (2)

Now, when the net gravitational force is zero, the both the gravitational force and electro static force mut be equal:

Equating eqn (1) and (2):

$\frac{GM_{E}M_{M}}{d^{2}} = \frac{1}{4\pi\epsilon_{o}}\frac{Q^{2}}{d^{2}}$

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$\sqrt{\farc{(6.67\times 10^{- 11})\times (5.98\times 10^{24})\times (7.35\times 10^{22})}{9\times 10^{9}}} = Q$

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Can a body have momentum without energy?

mestny [16]

No it does not! As it is not moving?!

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3 years ago

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Fittoniya [83]

A charged particle has an electrostatic field surrounding it.

When the particle is in motion, the moving charge is an
electric current, and that has a magnetic field around it.

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