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coldgirl [10]
3 years ago
11

In a circuit, a variable resistor is to be connected across a potential difference of 60 volts to allow the current to be adjust

ed in the range from 40 milliamperes to 100 milliamperes.
A variable resistor is a device in which the resistance can be varied.
mA = milliamperes, or 10-3 amperes
Over what range must the resistance vary?

plz help :')
Physics
1 answer:
sweet [91]3 years ago
4 0

Answer:

600 and 1500 [ohm

Explanation:

To solve this problem we must use ohm's law, which tells us that the voltage is the product of the current by the resistance, so we have:

V = I*R

where:

V = voltage [V]

I = current [amp]

R = resistance [ohm]

<u>Therefore:</u>

R = V/I

R1 = 60/(40*10^-3) = 1500 [ohm]

R2 = 60/(100*10^-3) = 600 [ohm]

So the resistance should be among 600 and 1500 [ohm]

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7.8cm

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A bowling ball rolls 33\,\text m33m33, start text, m, end text with an average speed of 2.5\,\dfrac{\text m}{\text s}2.5 s m ​ 2
asambeis [7]

The ball rolled for 13.2 s

<h3>Further explanation</h3>

Speed is scalar and no direction

\tt avg~speed=\dfrac{total~distance}{elapsed~time}=\dfrac{\Delta x}{\Delta t}

A bowling ball rolls 33 m, with average speed = 2.5 m/s

So elapsed time :

\tt t=\dfrac{33~m}{2.5`m/s}=13.2~s

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3 years ago
Suppose a cup of coï¬ee is at 100 degrees Celsius at time t = 0, it is at 70 degrees at t = 10 minutes, and it is at 50 degrees
Alexandra [31]

Answer:

T ambient = 10 degrees

Explanation:

Using Newton's Law of Cooling:

T(t) = Tamb + (Ti - Tamb)*e^(-kt)  ..... Eq 1

Ti = 100

We have two points to evaluate the above equation as follows:

T = 70 @ t = 10 using Eq 1  

70 = Tamb + (100 - Tamb)*e^(-10k)   ... Eq 2

T = 50 @ t = 20 using Eq 1

50 = Tamb + (100 - Tamb)*e^(-20k)   ... Eq 3

Solving the above Eq 2 and Eq 3 simultaneously:

Using Eq 2:

(70 - Tamb) / (100 - Tamb) = e^(-10k)  

Squaring both sides we get:

((70 - Tamb) / (100 - Tamb))^2 = e^(-20k)   .... Eq 4

Substitute Eq 4 into Eq 3

50 = Tamb + (100 - Tamb)*((70 - Tamb) / (100 - Tamb))^2

After simplification:

50 = (Tamb (100-Tamb) + (70-Tamb)^2) / (100 - Tamb)

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Tamb = 100 / 10 = 10 degrees

6 0
3 years ago
Does changing position of charges change the magnitude
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No, they will not change.

Explanation:

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If your hair blower isnt rated for 220- 230V(this is the voltage in EU) you are most likely going to burn it.
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