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mestny [16]
3 years ago
15

A 25-kg child sits at the top of a 4-meter slide. After sliding down, the child is traveling at 5 m/s. How much PE does he start

with? How much KE does he end with? How much energy is lost to friction?
Physics
1 answer:
Semmy [17]3 years ago
4 0

Daniddmelo says it right there, don't know why he got reported.

The potential energy (PE) is mass x height x gravity. So it would be 25 kg x 4  m x 9.8 = 980 joules. The child starts out with 980 joules of potential energy. The kinetic energy (KE) is (1/2) x mass x velocity squared. KE = (1/2) x 25 kg x 5 m/s2 = 312.5 joules. So he ends with 312.5 joules of kinetic energy. The Energy lost to friction =  PE - KE. 980- 312.5 = 667.5 joules of energy lost to friction.

Please don't just copy and paste, and thank you Dan cause you practically did it I just... elaborated more? I dunno. 

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Two loudspeakers placed 6.0 m apart are driven in phase by an audio oscillator, whose frequency range is 1595 to 2158 Hz. A poin
denpristay [2]

Answer:

The frequency produced by the oscillator, for which destructive interference occurs at point P, in the range of frequencies for the oscillator = 2033 Hz

Explanation:

For destructive interference, the difference in path length of the waves from each loudspeaker is related to the wavelength through.

(m + ½)λ = |d₁ - d₂|

where m can take on positive whole number values 0,1,2,3...

Point P is 4.7 m from A and 3.6 m from B

d₁ = 4.7 m

d₂ = 3.6 m

|d₁ - d₂| = 4.7 - 3.6 = 1.1 m

(m + ½)λ = |d₁ - d₂| = 1.1

(m + ½)λ = 1.1

where m could be any whole number from 0,1,2...

And the relationship between velocity of a wave, v, its frequency, f, and the wavelength, λ, is given as

v = fλ

The frequency range of the audio oscillator is frequency range is 1595 to 2158 Hz.

We can find a wavelength for the sound within this range, so as to obtain the exact frequency.

The options include 2001, 2033, 2127, 2095, or 2064 Hz.

Taking just 1 frequency in that range, f = 2033 Hz.

v = fλ

λ = (v/f) = (344/2033) = 0.169 m

Inserting in the destructive interference equation

(m + ½)λ = 1.1

If λ = 0.169 m

(m + ½) = (1.1/0.169) = 6.5

m + ½ = 6.5

Hence, it is evident that m = 6 for this question.

And the corresponding frequency at this level of destructive interference is 2033 Hz

Hope this Helps!!!

8 0
4 years ago
If the torque required to loosen a nut that holds a wheel on a car has a magnitude of 55 n·m, what force must be exerted at the
erastova [34]

Either 175 N or 157 N depending upon how the value of 48° was measured from.    
You didn't mention if the angle of 48° is from the lug wrench itself, or if it's from the normal to the lug wrench. So I'll solve for both cases and you'll need to select the desired answer.    
Since we need a torque of 55 N·m to loosen the nut and our lug wrench is 0.47 m long, that means that we need 55 N·m / 0.47 m = 117 N of usefully applied force in order to loosen the nut. This figure will be used for both possible angles.    
Ideally, the force will have a 0° degree difference from the normal and 100% of the force will be usefully applied. Any value greater than 0° will have the exerted force reduced by the cosine of the angle from the normal. Hence the term "cosine loss".     
If the angle of 48° is from the normal to the lug wrench, the usefully applied power will be:  
U = F*cos(48)  
where  
U = Useful force  
F = Force applied    
So solving for F and calculating gives:  
U = F*cos(48)  
U/cos(48) = F  
117 N/0.669130606 = F  
174.8537563 N = F    
So 175 Newtons of force is required in this situation.    
If the 48° is from the lug wrench itself, that means that the force is 90° - 48° = 42° from the normal. So doing the calculation again (this time from where we started plugging in values) we get  
U/cos(42) = F  
117/0.743144825 = F  
157.4390294 = F    
Or 157 Newtons is required for this case.
6 0
3 years ago
The geocentric model of the universe stated that _____.
Natalka [10]
Earth was the center of the universe
7 0
3 years ago
Read 2 more answers
How do you post a picture
BARSIC [14]
Click the ask a question button or answer button then at the bottom above the keyboard there are two little icons. A camera lens and a Mountain View. If you click the camera lens you can take a picture to post and if you click the Mountain View it will give you the option to post a picture from your photos.
4 0
3 years ago
All of the following steps are included in a self-modification program except __________. A. specifying target behavior B. desig
Y_Kistochka [10]

Answer:

C)focusing on one goal at a time

Explanation:

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✓ specifying target behavior ✓designing a program

✓ gathering data about target behavior

8 0
3 years ago
Read 2 more answers
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