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2 years ago

11

Wood has chemical energy which can be used to generate thermal and radiant energy when burned in a fire place which best explain

s what happens to the total amount of energy in this scenario

2 answers:

creativ13 [48]2 years ago

5 0

Answer:

the answer is b:D

Explanation:

vitfil [10]2 years ago

5 0

Answer:

c i took the test

Explanation:

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Anvisha [2.4K]

The speed of the rock at 20 m is 34.3 m/s

Explanation:

We can solve this problem by using the law of conservation of energy: the mechanical energy of the rock, sum of its potential energy + its kinetic energy) must be conserved in absence of air resistance. So we can write:

$U_i +K_i = U_f + K_f$

where :

$U_i$ is the initial potential energy

$K_i$ is the initial kinetic energy

$U_f$ is the final potential energy

$K_f$ is the final kinetic energy

The equation can also be rewritten as follows:

$mgh_i + \frac{1}{2}mu^2 = mgh_f + \frac{1}{2}mv^2$

where:

m = 100 kg is the mass of the rock

$g=9.8 m/s^2$ is the acceleration of gravity

$h_i = 80$ is the initial height

u = 0 is the initial speed (the rock starts at rest)

$h_f = 20 m$ is the final height of the rock

v is the final speed when h = 20 m

And solving for v, we find:

$v=\sqrt{2g(h_i-h_f)}=\sqrt{2(9.8)(80-20)}=34.3 m/s$

Learn more about kinetic energy and potential energy here:

brainly.com/question/6536722

brainly.com/question/1198647

brainly.com/question/10770261

#LearnwithBrainly

5 0

3 years ago

You do 120 j of work while pulling your sister back on a swing, whose chain is 5.10 m long. you start with the swing hanging ver

Goryan [66]

The work done to pull the sister back on the swing is equal to the increase in potential energy of the sister:
$W= \Delta U = mg \Delta h$ (1)

where m is the sister's mass, g is the gravitational acceleration and $\Delta h$ is the increase in altitude of the sister with respect to its initial position.

By calling $\theta$ the angle of the chain with respect to the vertical, the increase in altitude is given by
$\Delta h = L - L \cos \theta = L(1 - \cos \theta)$ (2)
where L is the length of the chain.

Putting (2) inside (1), we find
$W= m g L (1 - \cos \theta)$
from which we can find the mass of the sister:
$m = \frac{W}{g L (1 - \cos \theta)} = \frac{120 J}{(9.81 m/s^2)(5.10 m)(1- \cos 32.0^{\circ})} =15.8 kg$

5 0

2 years ago

A police officer is using her radar to check speeds. She is moving south at 50 mph. You are moving

Luda [366]

Answer:

the relative speed should be 40mph

Explanation:

8 0

2 years ago

How does the distance traveled by the coin compare to its displacement after ten flips?

Mkey [24]

Answer:

To calculate displacement, simply draw a vector from your starting point to your final position and solve for the length of this line. If your starting and ending position are the same, like your circular 5K route, then your displacement is 0. In physics, displacement is represented by Δs.

Explanation:

hope helps

5 0

2 years ago

A converging lens of focal length 20 cm is placed in contact with, and to the left of, a diverging lens of focal length 30 cm. I

scZoUnD [109]

Answer:

Magnification will be equal to 3

Explanation:

We have given focal length of the converging lens $F_1=20cm$

Focal length of the diverging lens $F_2=30cm$

Object is placed 40 cm to the length of the converging lens d = 40 cm

Combination of the focal length will be equal to

$\frac{1}{F}=\frac{1}{F_1}+\frac{1}{F_2}$

$\frac{1}{F}=\frac{1}{20}+\frac{1}{-30}=\frac{1}{20}-\frac{1}{30}=\frac{1}{60}$

F = 60 cm

So combination of the focal length will be 60 cm

Magnification is given by

$M=\frac{F}{F-d}=\frac{60}{60-40}=3$

So magnification will be equal to 3

3 0

3 years ago