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oee [108]
3 years ago
5

The superheroine Xanaxa, who has a mass of 67.5 kg , is pursuing the 70.3 kg archvillain Lexlax. She leaps from the ground to th

e top of a 179 m high building then dives off it and comes to rest at the bottom of a 15.9 m deep excavation where she finds Lexlax and neutralizes him. Does all this bring about a net gain or a net loss of gravitational potential energy?
Physics
1 answer:
Paladinen [302]3 years ago
4 0

Answer:

there is a net loss of potential energy  is Ut = -0.11 10⁵ J

Explanation:

The gravitational potential energy is

        ΔU = mg (y2- y1)

Where y1 is the initial position where the energy is defined as zero, in general in problems on the Earth's surface the reference system is taken at the lowest point, whereby y1 = 0 and consequently U1 = 0, this It is a matter of comfort since what matters are the changes in energy and not its value at one point explained.

Let's apply these concepts to our problem.

Jump from the ground to 179 m, let's calculate the energy change

     ΔU1 = mg (y2-y1)

     ΔU1 = 67.5 9.8 (179 -0)

     ΔU1 = 1.18 10⁵ J           gains energy

Dives up to Y3 = -15.9m below ground, therefore, this height is negative

The total height is y = 179 - (-15.9) = 194.9 m

       ΔU2 = mg (y3-y2)

These are the points where the dive begins and where it arrives

       ΔDU2 = 67.5 9.8 (- 194.9)

       ΔU2 = -1.29 105 J        loses energy

The total change in potential energy is

       Ut = ΔU1 + ΔU2

       Ut = 1.18 10⁵ - 1.29 10⁵

       Ut = -0.11 10⁵ J

Therefore, there is a net loss of potential energy

You can also calculate ΔU = mg (Δy)

Where ΔY is the change in body position, that is -15.9 m

         ΔU = 67.5 9.8 (-15.9)

         ΔU = -1.1 10⁴ J = -0.11 10⁵ J

You can see that it is the same value.

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A diffraction grating with 161 slits per centimeter is used to measure the wavelengths emitted by hydrogen gas. At what angles i
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Answer:

\theta_1  = 0.400^o

\theta_2   =0.378^o

Explanation:

From the question we are told that

    The  number of slits per cm is  k =  161\  slits\  per\  cm =  161 \  slits\  per\  0.01 m

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=>         d = 6.211 *10^{-5} \ m

Generally the condition for constructive interference is  

        n\lambda  =  d \ sin \theta

At  \lambda_1

      \theta _1  =  sin^{-1} [ \frac{1  *  434 *10^{-9}}{6.211 *10^{-5}} ]

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At  \lambda_2

       \theta _2  =  sin^{-1} [ \frac{1  *  410 *10^{-9}}{6.211 *10^{-5}} ]

       \theta_2   =0.378^o

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3 years ago
How many kilocalories are generated when the brakes are used to bring a 1200-kg car to rest from a speed of 95 km/h ? 1 kcal = 4
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Ethanol and biodoesel are also <u>cleaner-burning</u> fuels than pure gasoline and diesel fuel.

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