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3 years ago

How fast must a 2500-kg elephant move to have the same kinetic energy as a 67.0-kg sprinter running at 15.0 m/s

Physics

1 answer:

abruzzese [7]3 years ago

6 0

Answer:

2.45 m/s

Explanation:

kinetic energy = 1/2 * m * v^2

then, 0.5 * 2500 * x^2 = 0.5 * 67 * 15^2

by solving for x, X = 2.45 m/s

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Suppose you walk 11 m in a direction exactly 24° south of west then you walk 21 m in a direction exactly 39° west of north. 1) H

DENIUS [597]

Answer:

(1) 42.94 m

(2) $16.02^\circ$

Explanation:

Let us first draw a figure, for the given question as below:

In the figure, we assume that the person starts walking from point A to travel 11 m exactly $24^\circ$ south of west to point B and from there, it walks 21 m exactly $39^\circ$ west of north to reach point C.

Let us first write the two displacements in the vector form:

$\vec{AB} = (-11\cos 24^\circ\ \hat{i}-11\sin 24^\circ\ \hat{j})\ m =(-10.05\ \hat{i}-4.47\ \hat{j})\ m\\\vec{BC} = (-21\sin 39^\circ\ \hat{i}+21\cos 39^\circ\ \hat{j})\ m =(-31.22\ \hat{i}+16.32\ \hat{j})\ m$

Now, the vector sum of both these vectors will give us displacement vector from point A to point C.

$\vec{AC}=\vec{AB}+\vec{BC}\\\Rightarrow \vec{AC}=(-10.05\ \hat{i}-4.47\ \hat{j})\ m+(-31.22\ \hat{i}+16.32\ \hat{j})\ m\\\Rightarrow \vec{AC}=(-41.25\ \hat{i}+11.85\ \hat{j})\ m$

Part (1):

the magnitude of the shortest displacement from the starting point A to point the final position C is given by:

$AC=\sqrt{(-41.25)^2+(11.85)^2}\ m= 42.94\ m$

Part (2):

As the vector AC is coordinates lie in the third quadrant of the cartesian vector plane whose angle with the west will be positive in the north direction.

The angle of the shortest line connecting the starting point and the final position measured north of west is given by:

$\theta = \tan^{-1}(\dfrac{11.85}{41.27})\\\Rightarrow \theta = 16.02^\circ$

4 0

3 years ago

A physics student mounts two thin lenses along a single optical axis (the lenses are at right angles to the line connecting them

Tatiana [17]

Answer:

A) q₂ = 75.98 cm, B) q₂' = 115.38 cm, C)

Explanation:

A) This is an exercise in geometric optics, as the two lenses are separated by a greater distance than their focal lengths from each lens, they must be worked as independent lenses.

Lens 1. More to the left

let's use the constructor equation

$\frac{1}{f} = \frac{1}{p} + \frac{1}{q}$

where f is the focal length, p and q are the distance to the object and the image, respectively,

We must assume a distance to the object to perform the calculation, suppose that the object is 50 cm from lens 1 that is further to the left of the system.

$\frac{1}{q_1} = \frac{1}{f} - \frac{1}{p}$

$\frac{1}{q_1} = \frac{1}{14.8} - \frac{1}{50}$

1 / q₁ = 0.04756

q₁ = 21.0227 cm

this image is the object for the second lens that has f₂ = 14.8 cm

the distance must be measured from the second lens

p₂ = 39.4 -q₁

p₂ = 39.4 -21.0227

p₂ = 18.38 cm

let's use the constructor equation

1 / q₂ = 1 / f - 1 / p2

$\frac{1}{q_2} = \frac{1}{14.8} - \frac{1}{18.38}$

$\frac{1}{q_2}$ = 0.01316

q₂ = 75.98 cm

measured from the second lens

B) the position of the final image with respect to the first lens is

q₂’= q₂ + 39.4

q₂'= 75.98 +39.4

q₂' = 115.38 cm

C) the magnification of a lens is

m = - q / p

in this case the image measured from lens 2 is q2 = 75.98 cm

the distance to the object from the first lens is p1 = 50cm

m = - 75.98 / 50

m = -1.5 X

the negative sign indicates that the image is inverted

4 0

3 years ago

What is the unit of measurement for expressing the intensity of sound

Irina18 [472]

Decibel - the decibel is a relative unit of measurement equal to one 10th of a bel

5 0

3 years ago

Fe₂O3<br> + co<br> →<br> Fe3O4 + CO₂

Goryan [66]

Explanation:

Fe₂O₃ + CO → Fe₃O₄ + CO₂

Balancing the equation above, we can derive simple mathematical equations that are very easy to solve.

aFe₂O₃ + bCO → cFe₃O₄ + dCO₂

a,b,c and d are the coefficients needed to balance the equation above;

Conserving Fe; 2a = 3c

O: 3a + b = 4c + 2d

C: b = d

let a = 1;

c = $\frac{2}{3}$

Since b = d

3a + d = 4c + 2d

3a = 4c + 2d - d

3a = 4c + d

a = 1, c = $\frac{2}{3}$

3 = 4 x $\frac{2}{3}$ + d

d = $\frac{1}{3}$

b = $\frac{1}{3}$

multiplying a, b, c and d by 3:

a = 3 b = 1 c = 2 and d = 1

3Fe₂O₃ + CO → 2Fe₃O₄ + CO₂

Learn more:

Balanced equation brainly.com/question/2612756

#learnwithBrainly

6 0

3 years ago

If we can measure the period of a star's wobble caused by an orbiting planet, we know the _______.

Stells [14]

You would know the period of the planets orbit.

3 0

3 years ago