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4 years ago

PLSSSSS help how much gravitation potential energy does a 5kg object have when it is 10 meters off the ground????

1 answer:

5 0

Considering the equation for gravitational potential energy, PE=mgh, where m as mass, g as the acceleration due to gravity, and h has the height.

Substituting the numbers given, you’ll get (taking g as 9.81)

PE = 5 x 9.81 x 10

PE = 490.5 J

Therefore the gravitational potential energy will be 490.5 J

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How do the tension of the cord and the force of gravity affect a pendulum

azamat

The time period of the pendulum is affected by the acceleration due to gravity. The tension does not have any effect on the time period of the pendulum and also the mass of the bob does not effect the time period of the pendulum.

$T = 2 \pi \sqrt{\frac{l}{g}}$

Hence, if the gravity increases then the time period of the pendulum will decreases and it will swing faster.

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3 years ago

9. An object starting with a velocity of 20m/s accelerates to

Aliun [14]

Answer:

6.25 s

Explanation:

V=u+at

t= (v-u)/a

= (45-20)/4 = 6.25 s

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4 years ago

The interior space of large box is kept at 30 C. The walls of the box are 3 m high and have a ‘sandwich’ construction consisting

White raven [17]

Answer:

$\frac{\dot Q}{A} =20.129\ W.m^{-2}$

$T_1=27.58\ ^{\circ}C$ & $T_2=2.41875\ ^{\circ}C$

Explanation:

Given:

interior temperature of box, $T_i=30^{\circ}C$

height of the walls of box, $h=3\ m$

thickness of each layer of bi-layered plywood, $x_p=1.25\ cm=0.0125\ m$

thermal conductivity of plywood, $k_p=0.104\ W.m^{-1}.K^{-1}$

thickness of sandwiched Styrofoam, $x_s=5\ cm=0.05\ m$

thermal conductivity of Styrofoam, $k_s=0.04\ W.m^{-1}.K^{-1}$

exterior temperature, $T_o=0^{\circ}C$

From the Fourier's law of conduction:

$\dot Q=\frac{dT}{(\frac{x}{kA}) }$

$\dot Q=\frac{dT}{R_{th} }$ ....................................(1)

Now calculating the equivalent thermal resistance for conductivity using electrical analogy:

$R_{th}=R_p+R_s+R_p$

$R_{th}=\frac{x_p}{k_p.A}+\frac{x_s}{k_s.A}+\frac{x_p}{k_p.A}$

$R_{th}=\frac{1}{A} (\frac{x_p}{k_p}+\frac{x_s}{k_s}+\frac{x_p}{k_p})$

$R_{th}=\frac{1}{A} (\frac{0.0125}{0.104}+\frac{0.05}{0.04}+\frac{0.0125}{0.104})$

$R_{th}=\frac{1.4904}{A}$ .....................(2)

Putting the value from (2) into (1):

$\dot Q=\frac{30-0}{\frac{1.4904}{A} }$

$\dot Q=\frac{30\ A}{1.4904}$

$\frac{\dot Q}{A} =20.129\ W.m^{-2}$ is the heat per unit area of the wall.

The heat flux remains constant because the area is constant.

For plywood-Styrofoam interface from inside:

$\frac{\dot Q}{A} =k_p.\frac{T_i-T_1}{x_p}$

$20.129=0.104\times \frac{30-T_1}{0.0125}$

$T_1=27.58\ ^{\circ}C$

&For Styrofoam-plywood interface from inside:

$\frac{\dot Q}{A} =k_s.\frac{T_1-T_2}{x_s}$

$20.129=0.04\times \frac{27.58-T_2}{0.05}$

$T_2=2.41875\ ^{\circ}C$

4 0

3 years ago

What is the fate of solar radiation that reaches the earth?

expeople1 [14]

When solar radiation reaches the Earth it quickly dissipates as most of the radiation and UV rays are blocked by ozone layer, but more radiation and UV rays are able to get through because of global warming.

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3 years ago

What is true for ALL of the examples of electromagnetic waves? A) They all move at the same speed in a vacuum. B) They all have

gizmo_the_mogwai [7]

A statement that is true for ALL of the examples of electromagnetic waves is that;

A) They all move at the same speed in a vacuum

The reason for qualifying 'in vacuum' is because EM waves of different frequencies often propagate at different speeds through material. Generally speaking, we say that light travels in waves, and all electromagnetic radiation travels at the same speed which is about 3.0 * 108 meters per second through a vacuum.

5 0

3 years ago

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