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Sidana [21]
3 years ago
10

Who discovered natural magnet for the first time?​

Physics
1 answer:
andrew-mc [135]3 years ago
8 0
Answer: Magnes



Explanation: Magnes found that the nails and buckle of his sandals and the tip of his staff were attracted to the rock he was standing on. He dug up the Earth to find lodestones. Lodestones contain magnetite, a natural magnetic material Fe3O4.
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If it is known that a non-zero net force is acting on an object, then which of the
Anna [14]

Answer:

I think it is other B,C I think not fur sure though

7 0
3 years ago
The capacitance of the variable capacitor of a radio can be changed from 100 to 350 pF by turning the dial from 0° to 180°. With
tangare [24]

Answer:

0.7 mJ

Explanation:

<u>Identify the unknown:  </u>

The work required to turn the dial from 180° to 0°  

<u>List the Knowns:  </u>

Capacitance when the dial is set at 180°: C = 350 pF = 350 x 10^-12 F Capacitance when the dial is set at 0°: C = 100 pF = 100 x 10^-12 F  

Voltage of the battery: V = 130 V  

<u>Set Up the Problem:</u>  

<em><u>Energy stored in a capacitor: </u></em>

U_c=1/2*V^2*C

      =1/2*Q^2/C

<em><u>When the dial is set at 180°:</u></em><em>  </em>

U_c=1/2*(130)^2*350*10^-12=10^-4

Q=√2*U_c*C=4*10^-7

<u><em>When the dial is set at 0°:</em></u>  

U_c=1/2*(4*10^-7)^2/100*10^-12

      =8*10^-4 J

<u><em>Solve the Problem:  </em></u>

ΔU_c=7*10^-4 J

        =0.7 mJ

note:

there maybe error in calculation but method is correct

4 0
3 years ago
Read 2 more answers
Why we care about plastic and paper? Help me please!!!?
Vilka [71]
Well if we don't recycle paper and use it up too fast, more trees would be chopped down, which is not good for the environment. Plastic can be dangerous and release toxic chemicals so we have to handel it well. Btw, what grade are you in?
3 0
3 years ago
The velocity of a 640-kg auto is changed from 10.0 m/s to 44.0 m/s in 71.0 s by an external, constant force. (a) What is the res
n200080 [17]

Answer:

(a) <em>change in momentum of the car = 21760 kgm/s</em>

(b) <em>The magnitude of the force = 306.48 N</em>

Explanation:

<em>(a)</em>

<em>Change in momentum: </em><em>This is the product of mass and change in velocity. The unit of momentum is kgm/s. It can be expressed mathematically as,</em>

Change in momentum of the car = m(v-u)................. Equation 1

Where m = mass of the car, v = final velocity of the car, u = initial velocity of the car.

<em>Given: m = 640 kg, v = 44.0 m/s, u = 10.0 m/s.</em>

<em>Substituting these values into equation 1,</em>

<em>Change in momentum of the car = 640 (44-10)</em>

<em>change in momentum of the car = 640× 34</em>

<em>change in momentum of the car = 21760 kgm/s</em>

<em>change in momentum of the car = 21760 kgm/s</em>

<em>(b) Force:</em><em> Force of a body can be defined as the product of mass and its acceleration. It is measured in Newton (N). It can be expressed mathematically as,</em>

<em>Force = ma ................................ Equation 2</em>

<em> </em><em>    Or</em>

<em>Force = m(v-u)/t...................................... Equation 3</em>

<em>Where m = mass of the car, v = final velocity of the car, u = initial velocity of the car, a = acceleration of the car, t = time taken to change the velocity.</em>

<em>Given: m = 640 kg, u = 10.0 m/s v = 44 m/s, t = 71 s.</em>

<em>Substituting these values into equation 3</em>

<em>Force = 640(44-10)/71</em>

<em>Force = (640×34)/71</em>

<em>Force = 306.48 N</em>

<em>The magnitude of the force = 306.48 N</em>

3 0
3 years ago
Help immediately please
icang [17]

Answer:

Speed is a measure of how quickly an object moves from one place to another. It is equal to the distance traveled divided by the time.

3 0
3 years ago
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