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3 years ago

7

If a 60-watt bulb is used to light a room, how much current is flowing through the bulb given that the voltage is 120 volts?

1 answer:

Pavel [41]3 years ago

3 0

Well, if I understand correctly, I think it'd be 60, because 60+60= 120, but I may be wrong. It's not my best subject, but why not try to help even though I suck lol.

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A series LR circuit contains an emf source of 19 V having no internal resistance, a resistor, a 22 H inductor having no apprecia

masha68 [24]

Answer: R = 394.36ohm

Explanation: In a LR circuit, voltage for a resistor in function of time is given by:

$V(t) = \epsilon. e^{-t.\frac{L}{R} }$

ε is emf

L is indutance of inductor

R is resistance of resistor

After 4s, emf = 0.8*19, so:

$0.8*19 = 19. e^{-4.\frac{22}{R} }$

$0.8 = e^{-\frac{88}{R} }$

$ln(0.8) = ln(e^{-\frac{88}{R} })$

$ln(0.8) = -\frac{88}{R}$

$R = -\frac{88}{ln(0.8)}$

R = 394.36

In this LR circuit, the resistance of the resistor is 394.36ohms.

7 0

3 years ago

Balancing carefully, three boys inch out onto a horizontal tree branch above a pond, each planning to dive in separately. The th

VikaD [51]

Answer:

what is this a riddle lol it breaks when he either jumps or lands

Explanation:

3 0

3 years ago

If the resultant force acting on a 2.0 kg object is equal to (3.0î + 4.0ĵ) N, what is the change in kinetic energy as the object

12345 [234]

Answer:

ΔK = 24 joules.

Explanation:

Δ $K =$ Work done on the object

Work is equal to the dot product of force supplied and the displacement of the object.

$W = F$ * Δ $s$

Δ $s$ can be found by subtracting the vectors (7.0, -8.0) and (11.0, -5.0), which is written as Δ $s$ = (11.0 - 7.0, -5.0 - -8.0) which equals (4.0, 3.0).

This gives us

$W = < 3, 4 >$ * $< 4, 3 >$ = $(3*4)+(4*3)$ = $24$ J

3 0

1 year ago

Two friends, Al and Jo, have a combined mass of 195 kg. At the ice skating rink, they stand close together on skates, at rest an

ddd [48]

Answer:

Al's mass is 102.92 kg

Explanation:

As there are no external forces in the horizontal direction, the horizontal net force must be zero:

$F_{net} = 0$

As the force is the derivative in time of the momentum, this means that the horizontal momentum is constant:

$F_{net} = \frac{dp_{horizontal}}{dt} = 0$

$p_{horizontal_i }= p_{horizontal_f}$

where the suffix i and f means initial and final respectively.

The initial momentum will be:

$p_{horizontal_}i = m_{Al} \ v_{Al_i} + m_{Jo} \ v_{Jo_i}$

But, as they are at rest, initially

$p_{horizontal_i} = m_{Al} * 0 + m_{Jo} * 0$

$p_{horizontal_i} = 0$

So, this means:

$p_{horizontal_f} = m_{Al} \ v_{Al_f} + m_{Jo} \ v_{Jo_f} = 0$

We know that the have an combined mass of 195 kg:

$m_{total} = m_{Al} + m_{Jo} = 195 \ kg$ .

so:

$m_{Jo} = 195 \ kg - m_{Al}$ .

$m_{Al} \ v_{Al_f} + (195 \ kg - m_{Al}) \ v_{Jo_f} = 0$

$m_{Al} \ v_{Al_f} - m_{Al} \ v_{Jo_f}= - 195 \ kg \ v_{Jo_f}$

$m_{Al} \ (v_{Al_f} - v_{Jo_f})= - 195 \ kg \ v_{Jo_f}$

$m_{Al} = \frac{ - 195 \ kg \ v_{Jo_f} } { v_{Al_f} - v_{Jo_f} }$

$m_{Al} = \frac{195 \ kg \ v_{Jo_f} } { v_{Jo_f} - v_{Al_f} }$

Now, we can use the values:

$v_{Al_f}= 10.2 \frac{m}{s}$

$v_{Jo_f}= - 11.4 \frac{m}{s}$

where the minus sign appears as they are moving at opposite directions

$m_{Al} = \frac{195 \ kg ( - 11.4 \frac{m}{s} ) } { (- 11.4 \frac{m}{s}) - 10.2 \frac{m}{s} }$

$m_{Al} = 102.92 \ kg$

and this is the Al's mass.

5 0

3 years ago

A person travels from New York to Washington at the rate of 45 km per hour and

mr_godi [17]

Answer:

The average speed for the whole journey is 49.5 miles per hour.

Explanation:

Step 1 :

Here, both the ways, he covers the same distance. Then, the formula to find average speed is

= 2xy / (x+y)

Step 2 :

x ----> Rate at which he travels from New York to Washington

x = 45

y ----> Rate at which he travels from New York to Washington

y = 55

Step 3 :

So, the average speed is

= (2 ⋅ 45 ⋅ 55) / (45 + 55)

= 4950 / 100

= 49.5

8 0

3 years ago