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Stolb23 [73]
3 years ago
8

Simple Pendulum: A 34-kg child on an 18-kg swing set swings back and forth through small angles. If the length of the very light

supporting cables for the swing is 4.9 m, how long does it take for each complete back-and-forth swing
Physics
2 answers:
SIZIF [17.4K]3 years ago
5 0

Answer:

The correct answer is "4.443 sec".

Explanation:

Given:

Mass of child,

= 34 kg

Mass of swing,

= 18 kg

Length,

= 4.9 m

The time period of pendulum will be:

T = 2 \pi \sqrt{4g}

  = 2 \pi \sqrt{\frac{4.9}{9.8} }

  = 4.443 \ sec  

Tanya [424]3 years ago
5 0

Answer:

The time taken to back and forth is 4.4 s .

Explanation:

Length, L = 4.9 m

let the time period is T.

Acceleration due to gravity, g = 9.8 m/s^2

Use the formula of time period

T = 2 \pi\sqrt{L}{g}\\\\T = 2 \times 3.14\sqrt{4.9}{9.8}\\\\T = 4.4 s

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A car initially at rest accelerates at 10m/s^2. The car’s speed after it has traveled 25 meters is most nearly... A.) 0.0m/s B.)
STALIN [3.7K]

The car traverses a distance x after time t according to

x=\dfrac12at^2

where a is its acceleration, 10 m/s^2. The time it takes for the car to travel 25 m is

25\,\mathrm m=\left(5\dfrac{\rm m}{\mathrm s^2}\right)t^2\implies t=\sqrt 5\,\mathrm s

5 is pretty close to 4, so we can approximate the square root of 5 by 2. Then the car's velocity v after 2 s of travel is given by

v=\left(10\dfrac{\rm m}{\mathrm s^2}\right)(2\,\mathrm s)\approx20\dfrac{\rm m}{\rm s}

which makes C the most likely answer.

3 0
3 years ago
When waves of equal amplitude from two sources are out of phase when they interact it is called?
Verizon [17]
I believe destructive interference
6 0
3 years ago
An ultrasound unit is being used to measure a patient's heartbeat by combining the emitted 2.0 MHz signal with the sound waves r
alexandr402 [8]
Hi there, 
for this question we have:
Signal 2.0 MHz = Emitted so we can call it f_e
and we need the Reflected = f_{r}
In this question, we have a source which goes to the heart and a reflected which comes back from the heart and we need the speed of the reflected.
So you should know that the speed of reflected is lower than the source(Emitted). 
we also know: ΔBeat frequency(max) = 560 Hz = f_{b}
so we have: 
f_{e} - f_{r} = f_{b}
so frequency of Reflected is: 
2.0 × 10^6 Hz - 560 Hz = 1.99 × 10^6 Hz = f_{r}
now you know that Lambda = v/f 
so if we find the lambda with our Emitted then we can find v with the Reflected: 
Lambda = 1540(m/s) / 2.0 × 10^6 Hz = 7.7 × 10^-4 m 
=> v_{max} = (lambda)(f_{r} 
=> 7.7 × 10^-4m (1.99 × 10^6Hz) = 1532 m/s 
so the v_{max} is equal to 1532 m/s :)))
This question is solved by two top teachers as fast as they could :))
I hope this is helpful
have a nice day

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4 years ago
A 100-lb child stands on a scale while riding in an elevator. What does the scale read while the elevator slows to stop at the l
Lelechka [254]

Answer: A 100-lb child stands on a scale while riding in an elevator. Then, the scale reading approaches to 100lb, while the elevator slows to stop at the lowest floor

Explanation: To find the correct answer, we need to know more about the apparent weight of a body in a lift.

<h3>What is the apparent weight of a body in a lift?</h3>
  • Consider a body of mass m kept on a weighing machine in a lift.
  • The readings on the machine is the force exerted by the body on the machine(action), which is equal to the force exerted by the machine on the body(reaction).
  • The reaction we get as the weight recorded by the machine, and it is called the apparent weight.
<h3>How to solve the question?</h3>
  • Here we have given with the actual weight of the body as 100lbs.
  • This 100lb child is standing on the scale or the weighing machine, when it is riding .
  • During this condition, the acceleration of the lift is towards downward, and thus, a force of ma .
  • There is also<em> mg </em>downwards and a normal reaction in the upward direction.
  • when we equate both the upward force and downward force, we get,

                             ma=mg-N\\N=mg-ma    i.e. during riding the scale reads a weight less than that of actual weight.

  • When the lift goes slow and stops the lowest floor, then the acceleration will be approaches to zero.

Thus, from the above explanation, it is clear that ,when the elevator moves to the lowest floor slowly and stops, then the apparent weight will become the actual weight.

Learn more about the apparent weight of the body in a lift here:

brainly.com/question/28045397

#SPJ4

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Porque deja de funcionar una estufa electrica cuando la electricidad es excesiva??
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<h3>Porque deja de funcionar una estufa electrica cuando la electricidad es excesiva?</h3>

  • Es normal que los quemadores superiores de una estufa eléctrica o una estufa se enciendan y apaguen en configuraciones distintas a Hi. El quemador se encenderá y apagará más de lo normal cuando se utilizan cacerolas que no son planas o que son del tamaño incorrecto para el quemador.

<h2>☆彡Hanna</h2>

#CarryOnLearning

7 0
3 years ago
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