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4 years ago

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4. How does temperature affect the density of a material?

1 answer:

lara31 [8.8K]4 years ago

6 0

Answer:

Heating a substance causes molecules to speed up and spread slightly further apart, occupying a larger volume that results in a decrease in density. ... Hot water is less dense and will float on room-temperature water. Cold water is more dense and will sink in room-temperature water.

Explanation:

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A rock falls from the top of a cliff. What will happen to the rock's kinetic energy when it strikes the ground below?

Paha777 [63]

Answer:

B

Explanation:

It creates an equal amount of p energy.

REMEMBER: ENERGY CAN NEVER BE CREATED OR DESTROYED.

7 0

3 years ago

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The block in the drawing has dimensions L0×2L0×3L0,where L0 =0.5 m. The block has a thermal conductivity of 200 J/(s·m·C˚). In d

Dennis_Churaev [7]

Answer:

$Q_p=18000\ J$

$Q_o=8000\ J$

$Q_g=72000\ J$

Explanation:

Given:

Length of block, $l=3L_o=3\times 0.5=1.5\ m$

Breadth of block, $b=L_o=0.5\ m$

height of block, $h=2L_o=2\times 0.5=1\ m$

Thermal conductivity of the block, $k=200\ W.m.^{\circ}C$

Temperature on the hotter side, $T_H=37^{\circ}C$

temperature on the cooler side, $T_L=7^{\circ}C$

time for which the heat flows, $t=4\ s$

<u>REFER THE ATTACHED IMAGE FOR THE REFERENCE</u>

<em>The rate of heat flow using </em><em>Fourier's law</em><em> of conduction is given as:</em>

$\frac{Q}{t}=k.A.\frac{dT}{dx}$

<u>Now the amount heat flow perpendicular to the pink surface:</u>

$\frac{Q_p}{4}=200\times (0.5\times 1.5).\frac{30}{1}$

$Q_p=18000\ J$

<u>Now the amount heat flow perpendicular to the orange surface:</u>

$\frac{Q_o}{4}=200\times (0.5\times 1).\frac{30}{1.5}$

$Q_o=8000\ J$

<u>Now the amount heat flow perpendicular to the green surface:</u>

$\frac{Q_g}{4}=200\times (1.5\times 1).\frac{30}{0.5}$

$Q_g=72000\ J$

6 0

4 years ago

A 2.75 kg block is pulled across a flat, frictionless floor with a 5.11 N force directed 53.8° above horizontal. What is the tot

Softa [21]

Answer:

F = 3.01 N

Explanation:

Given that,

Mass of a block, m = 2.75 kg

Force applied to the block, F = 5.11 N

It is directed 53.8° above horizontal.

We need to find the total force acting on the block. The force acting on it is given by :

$F=F\cos\theta\\\\F=5.11\times \cos53.8\\F=3.01\ N$

So, 3.01 N of force is acting on the block.

4 0

3 years ago

Two blocks are connected by a massless rope that passes over a 1 kg pulley with a radius of 12 cm. The rope moves over the pulle

tangare [24]

Answer:

$F=1.159$

Explanation:

From the question we are told that:

Mass of pulley $M=1kg$

Radius $r=12cm$

Mass of block A $M_a=2.1kg$

Mass of block B $m_b=4.1kg$

Spring constant $\mu= 358 J/m2$

Generally the equation for Torque is mathematically given by

Since $\sumF=ma$

At mass A

$T_2-f_3=2.1a$

At mass B

$4.8-T_1=4.1a$

At Pulley

$R(T_1-T_2)=\frac{1*1*R^2}{2}\frac{a}{R}$

$R(T_1-T_2)=0.55a$

Therefore the equation for total force F

At mass A+At mass B+At Pulley

$(T_2-f_3+4.8-T_1+R(T_1-T_2)=2.1a+4.1a+0.55a$

$(T_2-f_3+4.8-T_1+R(T_1-T_2)=2.7a+4.8a+0.55a$

$-f_3+4.1=6.75a$

$-f_3=6.75a+4.8$

Since From above equation

$M_{eff}=6.7kg$

Therefore

$T=2\pi \sqrt{{\frac{M_{eff}}{k}}$

$T=2\pi \sqrt{{\frac{6.75}{\mu}}$

$T=0.862s$

Generally the equation for frequency is mathematically given by

$F=\frac{1}{T} \\F=\frac{1}{0.862}$

$F=1.159$

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3 years ago

Is hot asphalt that is poured into the ground and cools a physical or chemical change?

Gala2k [10]

Physical change
Because it's changed by heat

5 0

4 years ago

Read 2 more answers