4 years ago

Name three methods that can be used to change the overall density of an object.

Physics

1 answer:

Gnesinka [82]4 years ago

6 0

changing its shape
changing its mass
or changing its volume

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Which element has an atomic number of 9 and an atomic mass of 19?

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Answer:

fluorine

Explanation:

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3 years ago

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A 2.64-kg copper part, initially at 400 K, is plunged into a tank containing 4 kg of liquid water, initially at 300 K. The coppe

marin [14]

Answer:

a) $T_f=305.7049\ K$

b) $\Delta S=313.51\ J.K^{-1}$

Explanation:

Given:

mass of copper, $m_c=2.64\ kg$

initial temperature of copper, $T_{ic}=400\ K$

specific heat capacity of copper, $c_c=385\ J.kg^{-1}.K^{-1}$

mass of water, $m_w=4\ kg$

initial temperature of water, $T_{iw}=300\ K$

specific heat capacity of water, $c_w=4200\ J.kg^{-1}.K^{-1}$

∵No heat is lost in the environment and the heat is transferred only between the two bodies:

Heat rejected by the copper = heat absorbed by the water

$2.64\times 385\times (400-T_f)= 4\times 4200\times (T_f-300)$

$T_f=305.7049\ K$

Now the amount of heat transfer:

$Q=m_c.c_c.(T_{ic}-T_{f})$

$Q=2.64\times 385\times (400-305.7049)$

$Q=95841.5841\ J$

∴Entropy change

$\Delta S=\frac{dQ}{T}$

$\Delta S=\frac{95841.5841}{305.7049}$

$\Delta S=313.51\ J.K^{-1}$

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4 years ago

A 1200 kg car accelerates from 13 m/s to 17 m/s. find the change in momentum of the car.

mixas84 [53]

P=4800kgm/s
As
p=mΔv
where p is momentum, m is mass and v is velocity
Given values is
m =1200kg
Δv= 17m/s-13m/s=4m/s
Now
p=mΔv
p=(1200kg)*(4m/s)
p=4800kgm/s

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2 years ago

A load of 25 kg is applied to the lower end and of a steal wire of length 25 m and thickness 3.0mm .The other end of wire is sus

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Answer:

the weight of the wire + 25kg

Explanation:

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3 years ago

A block is at rest. The coefficients of static and kinetic friction are s = 0.81 and k = 0.69, respectively. The acceleration of

lys-0071 [83]

Answer:

Explanation:

a ) The angle required = angle of repose = θ

Tanθ = .81

θ = 39⁰

b ) when angle of incline θ = 44

Net force on the block = mg sinθ - μ mg cosθ where μ is coefficient of kinetic friction

acceleration = gsinθ - μ g cosθ

= 9.8 ( sin44 - μ cos44 )

= 9.8 ( .695 - .69 x .72 )

= 9.8 ( .695 - .497 )

= 1.94 m /s²

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3 years ago