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3 years ago

Hey can someone send me the answer to this

Physics

1 answer:

bagirrra123 [75]3 years ago

5 0

Cars 'A' and 'C' look like they're moving at the same speed. If their tracks are parallel, then they're also moving with the same velocity.

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You set your stationary bike on a high 80-N friction-like resistive force and cycle for 30 min at a speed of 8.0 m/s . Your body

stellarik [79]

A) The change in internal chemical energy is $1.15\cdot 10^7 J$

B) The time needed is 1 minute

Explanation:

First of all, we start by calculating the power output of you and the bike, given by:

$P=Fv$

where

F = 80 N is the force that must be applied in order to overcome friction and travel at constant speed

v = 8.0 m/s is the velocity

Substituting,

$P=(80)(8.0)=640 W$

The energy output is related to the power by the equation

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

where:

P = 640 W is the power output

E is the energy output

$t = 30 min \cdot 60 = 1800 s$ is the time elapsed

Solving for E,

$E=Pt=(640)(1800)=1.15\cdot 10^6 J$

Since the body is 10% efficient at converting chemical energy into mechanical work (which is the output energy), this means that the change in internal chemical energy is given by

$\Delta E = \frac{E}{0.10}=\frac{1.15\cdot 10^6}{0.10}=1.15\cdot 10^7 J$

From the previous part, we found that in a time of

t = 30 min

the amount of internal chemical energy converted is

$E=1.15\cdot 10^7 J$

Here we want to find the time t' needed to convert an amount of chemical energy of

$E'=3.8\cdot 10^5 J$

So we can setup the following proportion:

$\frac{t}{E}=\frac{t'}{E'}$

And solving for t',

$t'=\frac{E't}{E}=\frac{(3.8\cdot 10^5)(30)}{1.15\cdot 10^7}=1 min$

Learn more about power and energy:

brainly.com/question/7956557

#LearnwithBrainly

3 0

2 years ago

How does Sonar work?i will mark brainliest pls help

Fittoniya [83]

I don't like the wording of any of the choices on the list.

SONAR generates a short pulse of sound, like a 'peep' or a 'ping',
focused in one direction. If there's a solid object in that direction,
then some of the sound that hits it gets reflected back, toward the
source. The source listens to hear if any of the sound that it sent
out returns to it. If it hears its own 'ping' come back, it measures
the time it took for the sound to go out and come back. That tells
the SONAR equipment that there IS a solid object in that direction,
and also HOW FAR away it is.

RADAR works exactly the same way, except RADAR uses radio waves.

5 0

3 years ago

Which of the following is most closely related to the specific heat of a substance?A. its temperatureB. its melting pointC. its

swat32

Answer:

option (C)

Explanation:

The amount of heat required to raise the temperature of substance of unit mass by unit degree is called specific heat of that substance.

Its SI unit is Joule / Kg °C.

Every material has a constant value of specific heat.

So, option (c) is correct.

4 0

3 years ago

Which of the following choices concerning the net magnetic flux through any enclosed surface is true according to Gauss' law for

11Alexandr11 [23.1K]

Answer:

e. The net magnetic flux in this case would be equal to zero.

Explanation:

As per Gauss law of magnetism we need to find the net magnetic flux through a closed loop

here we know that net magnetic flux is the scalar product of magnetic field vector and area vector

so here we have

$\int B. dA$ = net magnetic flux

since we know that magnetic field always forms closed loop so if we find the integral over a closed loop

then in that case the value of the close integral must be zero

so correct answer would be

e. The net magnetic flux in this case would be equal to zero.

6 0

3 years ago

Two parakeets sit on a swing with their combined center of mass 10.0 cm below the pivot. At what frequency do they swing?

Oksanka [162]

Answer:

1.58 Hz

Explanation:

The frequency of the simple pendulum is given by

f = 1/T

= 1/2π√g/l

In this problem, I = 10.0 cm = 0.1 m

f = 1/2π√9.8/0.1

= 1.58 Hz

7 0

3 years ago