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3 years ago

4. A high school athlete runs 400 m in 52.20 sec. What is his speed in mph? 14100 1110

Physics

1 answer:

Serggg [28]3 years ago

3 0

Answer:

28,800m/p second

Explanation:

Calculate the distance per second so, 400m/50 s= 8m/p second now knowing the speed/hour and knowing an hour has 3,600 seconds,multiply it by 8 then you will get 28,800m/p second, or 28.8km/h

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A rock climber wears a 8.1 kg backpack while scaling a cliff. After 28.2 min, the climber is 9.4 m above the starting point. How

mart [117]

Answer:

Explanation:

mass of backpack, m = 8.1 kg

weight of climber, W = 656 N

height raised, h = 9.4 m

time, t = 28.2 min = 28.2 x 60 = 1692 second

weight of backpack, w = m x g = 8.1 x 9.8 = 79.38 N

Work done by the climber on the backpack = mg x h = 79.38 x 9.4 = 746.17 J

Wok done in lifting herself + backpack = (W + w) x h

= (656 + 79.38) x 9.4 = 6912.57 J

Power developed by the climber,P = Total work / time

P = 6912.57 / 1692 = 4.09 W

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4 years ago

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bixtya [17]

Answer:

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Explanation:

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3 years ago

How can a small human retina detect objects larger than itself?

muminat

The correct answer would be A) the lenses of the eye change the size of images

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3 years ago

The parents of a young child carefully placed plastic plug protectors in all the electrical outlets in their house. Which statem

DanielleElmas [232]

I think the answer is c or b but i p ick c

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3 years ago

Read 2 more answers

Suppose electrons in a TV tube are accelerated through a potential difference of 2.00 104 V from the heated cathode (negative el

Ivanshal [37]

Answer:

83816746.4254 m/s

Explanation:

m = Mass of electron = $9.11\times 10^{-31}\ kg$

q = Charge of electron = $1.6\times 10^{-19}\ C$

V = Voltage = $2\times 10^4\ V$

The kinetic energy of the electron is

$K=\dfrac{1}{2}mv^2$

Energy is given by

$E=qV$

Balancing the energy

$qV=\dfrac{1}{2}mv^2\\\Rightarrow v=\sqrt{\dfrac{2qV}{m}}\\\Rightarrow v=\sqrt{\dfrac{2\times 1.6\times 10^{-19}\times 2\times 10^4}{9.11\times 10^{-31}}}\\\Rightarrow v=83816746.4254\ m/s$

The velocity of the electrons is 83816746.4254 m/s

5 0

3 years ago