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brilliants [131]
3 years ago
7

The superheroine Xanaxa, who has a mass of 68.1 kg , is pursuing the 75.3 kg archvillain Lexlax. She leaps from the ground to th

e top of a 193 m high building then dives off it and comes to rest at the bottom of a 16.1 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:
Alexandra [31]3 years ago
4 0

The concept required to solve this problem is associated with potential energy. Recall that potential energy is defined as the product between mass, gravity, and change in height. Mathematically it can be described as

U = mg\Delta h

Here,

\Delta h = Change in height

m = mass of super heroine

g = Acceleration due to gravity

The change in height will be,

\Delta h = h_f - h_i

The final position of the heroin is below the ground level,

h_f = -16.1m

The initial height will be the zero point of our system of reference,

\Delta h = -16.1m-0m

\Delta h = -16.1m

Replacing all this values we have,

U = mg\Delta h

U = (68.1kg)(9.8m/s^2)(-16.1m)

U = -10744.81J

Since the final position of the heroine is located below the ground, there will net loss of gravitational potential energy of 10744.81J

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A train traveling at 25 m/s is blowing its whistle at 440 Hz as it crosses a level crossing. You are waiting at the crossing and
ohaa [14]

Answer:

b) 472HZ, 408HZ

Explanation:

To find the frequencies perceived when the bus approaches and the train departs, you use the Doppler's effect formula for both cases:

f_o=f\frac{v_s+v_o}{v_s-v}\\\\f_o=f'\frac{v_s-v_o}{v_s+v}\\\\

fo: frequency of the source = 440Hz

vs: speed of sound = 343m/s

vo: speed of the observer = 0m/s (at rest)

v: sped of the train

f: frequency perceived when the train leaves us.

f': frequency when the train is getTing closer.

Thus, by doing f and f' the subjects of the formulas and replacing the values of v, vo, vs and fo you obtain:

f=f_o\frac{v_s-v}{v_s+v_o}=(440Hz)\frac{340m/s-25m/s}{340m/s}=408Hz\\\\f'=f_o\frac{v_s+v}{v_s-v_o}=(440Hz)\frac{340m/s+25m/s}{340m/s}=472Hz

hence, the frequencies for before and after tha train has past are

b) 472HZ, 408HZ

6 0
3 years ago
The odometer of a car changes from 1048 km to 1096 km in 40
Makovka662 [10]

Answer:

20m/s

Explanation:

it covers 20 metres in a second

3 0
2 years ago
An L-R-C series circuit, R = 160 Ω , L = 0.790 H , and C = 1.30×10−2 μF . The source has a voltage amplitude of 140 V and a freq
wolverine [178]

Answer: a) 1 b) 61 W c) 61 W

Explanation:

a) The  Power Factor (also known as cos φ), is defined by the difference in phase between current and voltage, in a RLC series circuit, and is expressed as follows:

cos φ = R / Z = R / \sqrt{(R)^{2} + (Xl -Xc)^{2} }

In resonance, XL =XC, so the circuit behaves like it were purely resistive, so Z=R.

Replacing in the expression for power factor, we have:

cos φ = R/Z = R/R = 1

This means that in resonance, current and voltage are in phase each other.

b) The average power delivered by the source, in resonance, is simply the power dissipated at the resistance R, as follows:

Pavg = V² rms / R = V₀² / √2 / R = 61 W

c) If the circuit remains in resonance, the average power , which does not depends on frequency provided this condition remains, keeps the same, i.e. , 61 W.

7 0
3 years ago
how much time would it take for an airplane to reach its destination if it traveled at an average speed of 790 km/hr for a dista
NeTakaya
I think your question is incomplete because the distance between destination and departure point isn't given in the question

8 0
3 years ago
Two oppositely charged but otherwise identical conducting plates of area 2.50 square centimeters are separated by a dielectric 1
TEA [102]

Answer: 38.2 μC

Explanation: In order to solve this problem we have to use the relationship for a two plate capacitor with a dielectric  so:

C= Q/V= we also know that for two paralel plates C=εo*k*A/d and V=E/d

where k is the dielectric constant, A plate area, V is potential difference; E electric field and d the separation between the plates.

reorganizing we have:

Q/A=σ= E*k/εo= 1.2 * 10^6*3.6/8.85 * 10^-12=38.2μC

3 0
2 years ago
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