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Over [174]
4 years ago
13

At what distance will a 45 W lightbulb have the same apparent brightness as a 130 W bulb viewed from a distance of 35 m ? (Assum

e that both bulbs convert electrical power to light with the same efficiency, and radiate light uniformly in all directions.)
Physics
1 answer:
Sloan [31]4 years ago
5 0

Answer:

20.6 m

Explanation:

P₁ = Power of first bulb = 45 W

P₂ = Power of second bulb = 130 W

r₁ = distance from the first bulb

r₂ = distance from the second bulb = 35 m

Using the equation

\frac{P_{1}}{r_{1}^{2}} = \frac{P_{2}}{r_{2}^{2}}

Inserting the values

\frac{45}{r_{1}^{2}} = \frac{130}{35^{2}}

r₁ = 20.6 m

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costa rica does not have deserts hoped this helped and have a great day:)


7 0
3 years ago
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Suppose oil spills from a ruptured tanker and spreads in a circular pattern. If the radius of the oil spill increases at a const
Dafna1 [17]

Answer:

\frac{dA}{dt} = 188.5 m^2/s

Explanation:

As we know that area of the circle at any instant of time is given as

A = \pi r^2

now in order to find the rate of change in area we will have

\frac{dA}{dt} = 2\pi r\frac{dr}{dt}

here we know that

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\frac{dr}{dt}= 1 m/s

radius of the circle is given as

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8 0
4 years ago
While a block slides forward 1.35 m, a force pulls back at a 135 direction, doing -17.8 J of work. what is the magnitude of the
Mademuasel [1]
<h2>18.6467 N</h2>

Explanation:

       The Work done by any force is defined as the force applied times the displacement of point of application of force in the direction of force.

       This is better represented as a scalar product of Force vector and displacement vector.

       Work\textrm{ = }\vec{F}.\vec{s}

Here, the angle between force and displacement is 145^{o}.

       Work=|F||s|\cos\theta

       -17.8\textrm{ J = }|F|\times 1.35\textrm{ }m\times cos(135^{o})

       |F|=18.6467N

∴ Magnitude of force = 18.6467N

3 0
3 years ago
A square loop of wire with a small resistance is moved with constant speed from a field free region into a region of uniform B f
Misha Larkins [42]

Answer:

A) False

B) False

C) True

D) False

Explanation:

A) False, because when leaving the field, the coil experiences a magnetic force to the right.

B) When the loop is entering the field, the magnetic flux through it will increase. Thus, induced magnetic field will try to decrease the magnetic flux i.e. the induced magnetic field will be opposite to the applied magnetic field. The applied magnetic field is into the plane of figure and thus the induced magnetic field is out of the plane of figure. Due to that reason, the current would be counterclockwise. So the statement is false.

C) When the loop is leaving the field, the magnetic flux through the loop will decrease. Thus, induced magnetic field will try to increase the magnetic flux i.e. the inducued magnetic field will be in the same direction as the applied magnetic field. The applied magnetic field is into the plane of figure and thus the induced magnetic field is also into the plane of figure. Due to that reason, the current would be clockwise. So the statement is true.

D) False because when entering the field magnetic force will be toward left side

8 0
3 years ago
pakka acquires a velocity of 72 km per hour in 10 seconds starting from rest find a ) the acceleration b)the average velocity c)
nadezda [96]
Acceleration equals 24 km/s
Average equals 396km/s
8 0
4 years ago
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