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3 years ago

This is a textbook question, work too please!

Physics

1 answer:

lara [203]3 years ago

4 0

The force is not pulling in the direction that the box is moving.
Only the force in the horizontal direction does work.
The force in the vertical direction doesn't do any work, because
   the box doesn't move through any vertical distance.

The horizontal force is 200(cos 45°) = 142 newtons

The vertical force is 200(sin 45°) = 142 newtons

If you pull the box 5 meters, then the amount of work done is

   (force) x (distance) = (142 N) x (5 m) = 710 joules.

Power = (work done) / (time to do the work)

   = (710 joules) / (5 seconds) = 142 watts .

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Imagine you are holding an apple. a. Does this apple have energy? How do you know? b. How could you increase the potential energ

Len [333]

A). The apple has thermal energy, because its temperature is higher
than absolute zero.
It also has chemical energy, because if I eat it, I get a burst of energy
and I become ambitious for a while.
It also has gravitational potential energy, because if I drop it on my foot,
it could bruise one of my piggies.

b). I could increase its potential energy by lifting it higher, like over my head.

c). As long as I'm just holding the apple, it doesn't have any kinetic energy.
I could give it some kinetic energy by throwing it.
Or I could just drop it, and let gravity give it kinetic energy.

7 0

3 years ago

A fan at a rock concert is 50.0 m from the stage, and at this point the sound intensity level is 114 dB. Sound is detected when

Marianna [84]

Answer:

A) $P=13.92\ J.s^{-1}$

B) $v=3730.9912\ m.s^{-1}$

C) $v=74.44\ mm.s^{-1}$

D) mosquitoes speed in part B is very much larger than that of part C.

Explanation:

Given:

Distance form the sound source, $s=50\ m$

sound intensity level at the given location, $\beta=114\ dB$

diameter of the eardrum membrane in humans, $d=8.4 \times 10^{-3}\ m$

We have the minimum detectable intensity to the human ears, $I_0=10^{-12}\ W.m^{-2}$

(A)

Now the intensity of the sound at the given location is related mathematically as:

$\beta=10\ log(\frac{I}{I_0} )$ ..........................................(1)

$114=10\ log\ (\frac{I}{10^{-12}} )$

$11.4=log\ I+12\ log\ 10$

$I=0.2512\ W.m^{-2}$

As we know :

$I=\frac{P}{A}$

$0.2512=\frac{P}{\pi\times \frac{8.4^2}{4} }$

$P=13.92\ J.s^{-1}$ is the energy transferred to the eardrums per second.

(B)

mass of mosquito, $m=2\times 10^{-6}\ kg$

Now the velocity of mosquito for the same kinetic energy:

$KE=\frac{1}{2} m.v^2$

$13.92=\frac{1}{2}\times 2\times 10^{-6}\times v^2$

$v=3730.9912\ m.s^{-1}$

(C)

Given:

Sound intensity, $\beta = 20\ dB$

Using eq. (1)

$20=10\ log\ (\frac{I}{10^{-12}} )$

$2=log\ I+12\ log\ 10$

$I=10^{-10}\ W.m^{-2}$

Now, power:

$P=I.A$

$P=10^{-10}\times \pi\times \frac{8.4^2}{4}$

$P=5.54\times 10^{-9}\ J.s^{-1}$

Hence:

$KE=\frac{1}{2} m.v^2$

$5.54\times 10^{-9}=0.5\times 2\times 10^{-6}\times v^2$

$v=0.07444\ m.s^{-1}$

$v=74.44\ mm.s^{-1}$

(D)

mosquitoes speed in part B is very much larger than that of part C.

7 0

3 years ago

Using evidence from the article, defend the concept that Earth’s magnetic poles have swapped places over time.

Mamont248 [21]

Answer: Scientists found evidence of Earths magnetic field reversal in rocks on the ocean floor at plate boundaries. These rocks have alternating polarity due to magnetization that occurred during their cooling period. Using radio metric dating, scientist estimate that reversals occur approximately every several hundred thousand years.

Explanation:

6 0

3 years ago

Countries such as Ireland, Germany and the UK use wind turbines to generate power. How does a wind turbine transform energy?

kiruha [24]

Answer:

Rf5 is 6 and I have an article on common strategies for coping

Explanation:

Abdullah and this is my 55 566 and I have an article on common strategies for coping with the value of polynomial 5x and the video will will certainly not cause any harm to you and the thank god that you can please make a gaming video or 6 with gggtgr and the video will will certainly be the same as the one you sent me last night and I will send you a link to the chief 6 on the

3 0

3 years ago

One strategy in a snowball at a high angle over level ground. While your opponent is watching this first snowball, you throw a s

siniylev [52]

Answer:

33°

Explanation:

We are given;

Speed at which both snowballs are thrown; v = 33.2 m/s

Angle at which snowballs are thrown with respect to the horizontal; θ = 57°

Now,we want to find out the angle at which the second snowball should be thrown in order to arrive at the same point as the first.

To calculate this angle, we will use complementary angle concept.

Now, because the target is in the same place, there will be two launch angles that will make the snow ball to be placed on the target.

The is calculated from;θ1 = 45° - (57° - 45°) = 33°

8 0

3 years ago