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Vedmedyk [2.9K]
2 years ago
8

Calculate the power of a train that uses 2MJ of chemical energy in 4 seconds.

Physics
1 answer:
nadya68 [22]2 years ago
6 0

Answer:

500 kW

Explanation:

Given that,

Energy of the train, E = 2 MJ = 2×10⁶ J

Time, t = 4 seconds

We need to find the power of the train. We know that,

Power = energy/time

So,

P=\dfrac{2\times 10^6}{4}\\\\P=500000\ W\\\\or\\\\P=500\ kW

So, the power of the train is equal to 500 kW.

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A 525 kg satellite is in a circular orbit at an altitude of 575 km above the Earth's surface. Because of air friction, the satel
Dafna1 [17]

Answer:

1.69\cdot 10^{10}J

Explanation:

The total energy of the satellite when it is still in orbit is given by the formula

E=-G\frac{mM}{2r}

where

G is the gravitational constant

m = 525 kg is the mass of the satellite

M=5.98\cdot 10^{24}kg is the Earth's mass

r is the distance of the satellite from the Earth's center, so it is the sum of the Earth's radius and the altitude of the satellite:

r=R+h=6370 km +575 km=6945 km=6.95\cdot 10^6 m

So the initial total energy is

E_i=-(6.67\cdot 10^{-11})\frac{(525 kg)(5.98\cdot 10^{24} kg)}{2(6.95\cdot 10^6 m)}=-1.51\cdot 10^{10}J

When the satellite hits the ground, it is now on Earth's surface, so

r=R=6370 km=6.37\cdot 10^6 m

so its gravitational potential energy is

U = -G\frac{mM}{r}=-(6.67\cdot 10^{-11})\frac{(525 kg)(5.98\cdot 10^{24}kg)}{6.37\cdot 10^6 m}=-3.29\cdot 10^{10} J

And since it hits the ground with speed

v=1.90 km/s = 1900 m/s

it also has kinetic energy:

K=\frac{1}{2}mv^2=\frac{1}{2}(525 kg)(1900 m/s)^2=9.48\cdot 10^8 J

So the total energy when the satellite hits the ground is

E_f = U+K=-3.29\cdot 10^{10}J+9.48\cdot 10^8 J=-3.20\cdot 10^{10} J

So the energy transformed into internal energy due to air friction is the difference between the total initial energy and the total final energy of the satellite:

\Delta E=E_i-E_f=-1.51\cdot 10^{10} J-(-3.20\cdot 10^{10} J)=1.69\cdot 10^{10}J

8 0
3 years ago
How can meteorologists use the jet stream to predict the weather ?
barxatty [35]
<span>Jet streams act as an invisible director of the atmosphere and are largely responsible for changes in the weather across the globe.
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5 0
3 years ago
The LR5 is the specialist submarine for underwater rescue. The average density of seawater is 1028 kg/ m3.
sladkih [1.3K]

Answer:

P = 7196 [kPa]

Explanation:

We can solve this problem using the expression that defines the pressure depending on the height of water column.

P = dens*g*h

where:

dens = 1028 [kg/m^3]

g = 10 [m/s^2]

h = 700 [m]

Therefore:

P = 1028*10*700

P = 7196000 [Pa]

P = 7196 [kPa]

5 0
3 years ago
How long was a 60 W light bulb turned on if it used a total of 580 J of energy?
icang [17]
Here's the tool you need.  You can't answer the question without this:

           "1 watt"
means
           "1 joule of energy, generated, used, or moved, every second".

So      60 watts  =  60 joules per second

           Total energy generated,
            used, or moved                  = (power) x (time).

                                     580 joules  =  (60 watts) x (time)

Divide each side
by  (60 watts):              Time  =  (580 joules) / (60 joules/sec) 

                                               =  (9 and 2/3)  seconds  .
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3 years ago
What does it mean to say that wolves are social creatures
Marizza181 [45]
They interact with one another with their facial expressions and body movements all the time
5 0
3 years ago
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