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4 years ago

11

How much energy does a 100-W light bulb use in 10 s?

1 answer:

telo118 [61]4 years ago

8 0

Answer:c

Explanation:

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Which are uses of electromagnetic waves? Check all that apply.

Nat2105 [25]

The first, third, fourth, fifth and sixth

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4 years ago

Read 2 more answers

A motorcycle is following a car that is traveling at constant speed on a straight highway. Initially, the car and the motorcycle

xz_007 [3.2K]

Answer:

a) $\Delta{t} = 5.39s$

b) the motorcycle travels 155 m

Explanation:

Let $t_2-t_1 = \Delta{t}$ , then consider the equation of motion for the motorcycle (accelerated) and for the car (non accelerated):

$v_{m2}=v_0+a\Delta{t}\\x+d=(\frac{v_0+v_{m2}}{2} )\Delta{t}\\v_c = v_0 = \frac{x}{\Delta{t}}$

where:

$v_{m2}$ is the speed of the motorcycle at time 2

$v_{c}$ is the velocity of the car (constant)

$v_{0}$ is the velocity of the car and the motorcycle at time 1

d is the distance between the car and the motorcycle at time 1

x is the distance traveled by the car between time 1 and time 2

Solving the system of equations:

$\left[\begin{array}{cc}car&motorcycle\\x=v_0\Delta{t}&x+d=(\frac{v_0+v_{m2}}{2}}) \Delta{t}\end{array}\right]$

$v_0\Delta{t}=\frac{v_0+v_{m2}}{2}\Delta{t}-d \\\frac{v_0+v_{m2}}{2}\Delta{t}-v_0\Delta{t}=d\\(v_0+v_{m2})\Delta{t}-2v_0\Delta{t}=2d\\(v_0+v_0+a\Delta{t})\Delta{t}-2v_0\Delta{t}=2d\\(2v_0+a\Delta{t})\Delta{t}-2v_0\Delta{t}=2d\\a\Delta{t}^2=2d\\\Delta{t}=\sqrt{\frac{2d}{a}}=\sqrt{\frac{2*58}{4}}=\sqrt{29}=5.385s$

For the second part, we need to calculate x+d, so you can use the equation of the car to calculate x:

$x = v_0\Delta{t}= 18\sqrt{29}=96.933m\\then:\\x+d = 154.933$

3 0

3 years ago

A laser used for many applications of hard surface dental work emits 2780-nm wavelength pulses of variable energy (0-300 mJ) abo

Bess [88]

Answer:

a

$n = 1.119 *10^{18} \ photons$

b

$P = 1.6 \ W$

Explanation:

From the question we are told that

The wavelength is $\lambda = 2780 nm = 2780 *10^{-9} \ m$

The energy is $E = 80 mJ = 80 *10^{-3} \ J$

This energy is mathematically represented as

$E = \frac{n * h * c }{\lambda }$

Where c is the speed of light with a value $c = 3.0 *10^{8} \ m/s$

h is the Planck's constant with the value $h = 6.626 *10^{-34} \ J \cdot s$

n is the number of pulses

So

$n = \frac{E * \lambda }{h * c }$

substituting values

$n = \frac{80 *10^{-3} * 2780 *10^{-9}}{6.626 *10^{-34} * 3.0 *10^{8} }$

$n = 1.119 *10^{18} \ photons$

Given that the pulses where emitted 20 times in one second then the period of the pulse is

$T = \frac{1}{20}$

$T = 0.05 \ s$

Hence the average power of photons in one 80-mJ pulse during 1 s is mathematically represented as

$P = \frac{E}{T}$

substituting values

$P = \frac{ 80 *10^{-3}}{0.05}$

$P = 1.6 \ W$

6 0

4 years ago

What is the elastic potential energy of a spring that is compressed a distance of 0.35 m and has a spring constant of 71.8 N/m?

Vitek1552 [10]

Answer:

P.E = 4.398 Joules.

Explanation:

Given the following data;

Spring constant, k = 71.8N/m

Displacement, x = 0.35m

To find the elastic potential energy;

The elastic potential energy of an object is given by the formula;

$P.E = \frac {1}{2}kx^{2}$

Substituting into the equation, we have;

$P.E = \frac {1}{2}*71.8 *(0.35)^{2}$

$P.E = 35.9 * 0.1225$

Elastic potential energy = 4.398 Joules.

<em>Therefore, the elastic potential energy of the spring is 4.398 Joules. </em>

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3 years ago

Why are fossil fuels like coal, oil, and natural gas<br> called nonrenewable resources?

Elena L [17]

After they are all used up they can’t be renewed or used anymore.

3 0

4 years ago