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N76 [4]
3 years ago
7

The objective lens in a DVD player must move quickly to keep the laser beam focused on the disc's reflective layer. Why must thi

s lens have a very small mass?
Physics
1 answer:
Zinaida [17]3 years ago
4 0

Explanation:

The small mass of lens in a DVD player accounts for small inertia of the lens. Hence, even on application of force of small magnitude, the lens is rapidly accelerated. Moreover, the small mass of lens also accounts for lower resistance to change in its motion and therefore, again can be rapidly accelerated back and forth.

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6 0
3 years ago
Read 2 more answers
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
أسقط عامل حجرة من سطح بناية سقوطأ حرة. أوجد ما يلي :
Ilia_Sergeevich [38]

Answer:

??? i don't no what you just said

Explanation:

7 0
3 years ago
What does kidney disease affect the immune system
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It can hurt and harm the body on many different and levels 
6 0
4 years ago
Read 2 more answers
Define resistance and describe what would happen to a light bulb if the voltage increased but the resistance stayed the same. (h
PtichkaEL [24]

The light bulb would glow brighter.

<h3>What is Resistance?</h3>

a force that works against a body's direction of motion and seeks to stop or slow down motion, such as friction. a measure of how much a material prevents an electric current from flowing as a result of a voltage.

What is the law of resistance?

Resistance and Ohm's Law. According to Ohm's law, the resistance of the circuit and the current or energy travelling through the resistance are both exactly proportional to the voltage or potential difference between two places.

The current would grow since it is exactly proportionate to the voltage, increasing the light bulb's brilliance, or simply making it brighter.

to learn more about Resistance go to - brainly.com/question/15728236

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6 0
1 year ago
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