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In-s [12.5K]
2 years ago
5

Hicham El Guerrouj of Morocco holds the world record in the 1500 m running race. He ran the final 400 m in a time of 51.9 s.

Physics
1 answer:
konstantin123 [22]2 years ago
5 0

Answer: His average speed in mph over the last 400 m is 7.7 m/s.

Explanation:

Given: Hicham El Guerrouj of Morocco holds the world record in the 1500 m running race. He ran the final 400 m in a time of 51.9 s.

We know that , speed = \dfrac{distance}{time}

Here , distance = 400m and time = 51.9 s

Then, speed =  \dfrac{400}{51.9}\approx7.7\ m/s

Hence, his average speed in mph over the last 400 m is 7.7 m/s.

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If we double only the amplitude of a vibrating ideal mass-and-spring system, the mechanical energy of the system:
Lelechka [254]

Answer:

D. increases by a factor of 4.

Explanation:

General equation of SHM

Lets taken the general equation of the displacement given as

x = A sinω t

A=Amplitude ,t=time ,ω=natural frequency

We know that speed V

V=\dfrac{dx}{dt}

V= A ω cosωt

The mechanical energy of spring mass system

U=\dfrac{1}{2}KA^2

K=Spring constant

Now when Amplitude A become 2 times then the mechanical energy will become 4 times.

Therefore the answer is D.

8 0
2 years ago
A piano wire has a length of 81 cm and a mass of 2.0
choli [55]
<span>Frequency = 394 Hz
 Length of the string L = 81 cm = 0.81 m
 Mass of the string = 0.002 kg
 Tension T = ?
 Wave length of the string is two times the length.
  n x lambda = 2L, we also have lambda = vt = v / f, t is time period and given n = 1.
  Therefore L = v / 2f => v = 2fL
 Deriving form force equation, force here is tension T so
  v = squareroot of (TL/m) hence
   2fL = squareroot of (TL/m) => 4 x f^2 x L^2 = (T x L) / m => T = 4 x f^2 x L x m
 T = 4 x 0.81 x (394)^2 x 0.002 = 4 x 0.81 x 155236 x 0.002
 T = 1005.9 N = 1.006 x 10^3 N</span>
4 0
2 years ago
Which statement about images is correct? a) A virtual image cannot be formed on a screen. b) A virtual image cannot be viewed by
ankoles [38]

Answer:

A). A virtual image cannot be formed on a screen.

Explanation:

A virtual image can not be formed on a screen.

For image:

1.A virtual image can be viewed by the unaided eye.

2. A real image must be erect or maybe inverted.

3.Mirrors can produce virtual as well as real image ,it depends on which type of mirror is.

4.A virtual image can be photographed.

So the option A is correct.

5 0
2 years ago
charge, q1 =5.00μC, is at the origin, a second charge, q2= -3μC, is on the x-axis 0.800m from the origin. find the electric fiel
IRISSAK [1]

Answer:

Explanation:

Electric field due to charge at origin

= k Q / r²

k is a constant , Q is charge and r is distance

= 9 x 10⁹ x 5 x 10⁻⁶ / .5²

= 180 x 10³ N /C

In vector form

E₁ = 180 x 10³ j

Electric field due to q₂ charge

= 9 x 10⁹ x 3 x 10⁻⁶ /.5² + .8²

= 30.33 x 10³ N / C

It will have negative slope θ with x axis

Tan θ = .5 / √.5² + .8²

= .5 / .94

θ = 28°

E₂ = 30.33 x 10³ cos 28 i - 30.33 x 10³ sin28j

= 26.78 x 10³ i - 14.24 x 10³ j

Total electric field

E = E₁  + E₂

= 180 x 10³ j +26.78 x 10³ i - 14.24 x 10³ j

= 26.78 x 10³ i + 165.76 X 10³ j

magnitude

= √(26.78² + 165.76² ) x 10³ N /C

= 167.8 x 10³  N / C .

3 0
2 years ago
If a 1,300 kg car with no people inside is on the edge of a cliff 1,500 m above the ground, what is its potential energy?
Ghella [55]

<u>Given that</u>

mass (m) = 1300 Kg ,

height (h) = 1500 m

Determine the potential energy ?

     P.E = m × g × h

           = 1300 × 9.81 × 1500

           = 19129500  Joules

           = 19129.5 KJ

3 0
2 years ago
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