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mrs_skeptik [129]

3 years ago

8

A physicist does 100 joules of work on a simple machine that raise a box of bioks through a heigjt of 0.2metres. if the efficien

cy of the machine is 60%, how much work is converted to thermal energy?

1 answer:

11Alexandr11 [23.1K]3 years ago

5 0

Answer:

the work converted to thermal energy is 40 J.

Explanation:

Given;

work done by the physicist,w = 100 J

height through which the book is raised, h = 0.2 m

efficiency of machine = 60% = 0.6

The useful work done by the machine is calculated as;

useful work = 0.6 x 100 = 60 J

The wasted energy = 100 J - 60 J

The wasted energy = 40 J

The wasted energy by the machine is possibly converted to thermal energy by the frictional part of the machine.

Therefore, the work converted to thermal energy is 40 J.

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g Two cars, car 1 and car 2 are traveling in opposite directions, car 1 with a magnitude of velocity v1=13.0 m/s and car 2 v2= 7

bogdanovich [222]

Answer:

When they are approaching each other

$f_a = 2228.7 \ Hz$

When they are passing each other

$f_a = 2100Hz$

When they are retreating from each other

$f_a = 1980.7 Hz$

Explanation:

From the question we are told that

The velocity of car one is $v_1 = 13.0 m/s$

The velocity of car two is $v_2 = 7.22 m/s$

The frequency of sound from car one is $f_e = 2.10 kHz$

Generally the speed of sound at normal temperature is $v = 343 m/s$

Now as the cars move relative to each other doppler effect is created and this can be represented mathematically as

$f_a = f_o [\frac{v \pm v_o}{v \pm v_s} ]$

Where $v_s$ is the velocity of the source of sound

$v_o$ is the velocity of the observer of the sound

$f_o$ is the actual frequence

$f_a$ is the apparent frequency

Considering the case when they are approaching each other

$f_a = f_o [\frac{v + v_o}{v - v_s} ]$

$v_o = v_2$

$v_s = v_1$

$f_o = f_e$

Substituting value

$f_a = 2100 [\frac{343 + 7.22}{ 343 - 13} ]$

$f_a = 2228.7 \ Hz$

Considering the case when they are passing each other

At that instant

$v_o = v_s = 0m/s$

$f_o = f_e$

$f_a = f_o [\frac{v }{v } ]$

$f_a = f_o$

Substituting value

$f_a = 2100Hz$

Considering the case when they are retreating from each other

$f_a = f_o [\frac{v - v_o}{v + v_s} ]$

$v_o = v_2$

$v_s = v_1$

$f_o = f_e$

Substituting value

$f_a = 2100 [\frac{343 - 7.22}{343 + 13} ]$

$f_a = 1980.7 Hz$

7 0

3 years ago

A point charge with a charge q1 = 2.30 μC is held stationary at the origin. A second point charge with a charge q2 = -5.00 μC mo

Alla [95]

Answer:

W = 2.74 J

Explanation:

The work done by the charge on the origin to the moving charge is equal to the difference in the potential energy of the charges.

This is the electrostatic equivalent of the work-energy theorem.

$W = \Delta U = U_2 - U_1$

where the potential energy is defined as follows

$U = \frac{1}{4\pi\epsilon_0}\frac{q_1q_2}{r^2}$

Let's first calculate the distance 'r' for both positions.

$r_1 = \sqrt{(x_1 - x_0)^2 + (y_1 - y_0)^2} = \sqrt{(0.170 - 0)^2 + (0 - 0)^2} = 0.170~m\\r_2 = \sqrt{(x_2 - x_0)^2 + (y_2 - y_0)^2} = \sqrt{(0.250 - 0)^2 + (0.250 - 0)^2} = 0.353~m$

Now, we can calculate the potential energies for both positions.

$U_1 = \frac{kq_1q_2}{r_1^2} = \frac{(8.99\times 10^9)(2.3\times 10^{-6})(-5\times 10^{-6})}{(0.170)^2} = -3.57~J\\U_2 = \frac{kq_1q_2}{r_2^2} = \frac{(8.99\times 10^9)(2.3\times 10^{-6})(-5\times 10^{-6})}{(0.3530)^2} = -0.829~J$

Finally, the total work done on the moving particle can be calculated.

$W = U_2 - U_1 = (-0.829) - (-3.57) = 2.74~J$

4 0

3 years ago

Read 2 more answers

What objects can be seen from earth because they producde there own light? 

Lena [83]

- neon signs
- fireworks
- rockets during the ascent
- meteors
- fireflies
- stars

7 0

3 years ago

Which factors are used to calculate the kinetic energy of an object? Check all that apply. gravity velocity volume mass height

Sonja [21]

<em>Quantities that determine the kinetic energy of a body are its </em><em>mass and velocity </em>

Answer: <em>mass and velocity </em>

Explanation:

The kinetic energy of a body is the energy possessed by an object by virtue of its motion. It is given by the equation

$k= \frac{1}{2}mv^2$

Where m represents mass of the body and v represents its velocity.

Two bodies of equal velocity but different mass the heavier body will have greater kinetic energy. When an object is at rest its velocity is equal to zero. Thus its kinetic energy will be zero. Hence it can be concluded that only moving bodies have kinetic energy.

Stationary objects placed at a height possess potential energy which is the energy by virtue of their position or configuration. The total mechanical energy of a system is the sum of potential and kinetic energy.

8 0

3 years ago

Read 2 more answers

how much time would it take for an airplane to reach its destination if it traveled at an average speed of 790 km/hr for a dista

NeTakaya

I think your question is incomplete because the distance between destination and departure point isn't given in the question

8 0

3 years ago