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2 years ago

11

While skateboarding at 19 km/h, Alana throws a tennis ball at 11 km/h to her friend Oliver. If Alana is the reference frame, the

speed of the tennis ball is km/h.

2 answers:

Delvig [45]2 years ago

8 0

8 km/h I think good luck if it's wrong

dmitriy555 [2]2 years ago

6 0

the answer is 11 km/h ... i just took the test

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When the temperature of the air is 25 degress C, the velocity of a sound wave traveling through the air is approximately

dusya [7]

Assuming an ideal gas, the speed of sound depends on temperature
only. Air is almost an ideal gas.

Assuming the temperature of 25°C in a "standard atmosphere", the
density of air is 1.1644 kg/m3, and the speed of sound is 346.13 m/s.

The velocity can't be specified, since the question gives no information
regarding the direction of the sound.

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2 years ago

a sphere of diameter 6•0cm is moulded into a thin uniform wire of diameter 0•2mm.calculate the length of the wire in metres

Scilla [17]

The length of the wire is 36 m.

<u>Explanation:</u>

Given, Diameter of sphere = 6 cm

We know that, radius can be found by taking the half in the diameter value. So,

$\text { sphere radius, } R=\frac{D}{2}=\frac{6}{2}=3 \mathrm{cm}=3 \times 10^{-2} \mathrm{m}$

Similarly,

$\text { wire radius, } r=\frac{0.2}{2}=0.1 \mathrm{mm}=1 \times 10^{-3} \mathrm{m}$

We know the below formulas,

$\text {volume of sphere}=\frac{4}{3} \times \pi \times R^{3}$

$\text {volume of wire}=\pi \times r^{2} \times l$

When equating both the equations, we can find length of wire as below, where $\pi=\frac{22}{7}$

$\frac{4}{3} \times \pi \times R^{3}=\pi \times r^{2} \times l$

$\frac{4}{3} \times \frac{22}{7} \times\left(3 \times 10^{-2}\right)^{3}=\frac{22}{7} \times\left(1 \times 10^{-3}\right)^{2} \times l$

The $\pi$ value gets cancelled as common on both sides, we get

$\frac{4}{3} \times 27 \times 10^{-6}=10^{-6} \times l$

The $10^{-6}$ value gets cancelled as common on both sides, we get

$l=4 \times 9=36 m$

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2 years ago

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DedPeter [7]

<span>A+B-C
</span><span>A = 6x - 2y
B = -4x - 8y
C = -3x + 9y

(</span>6x - 2y) + (-4x - 8y) - (-3x + 9y)
(6x - 2y) + (-4x - 8y) + (3x - 9y)
2x -10y + (3x - 9y)

5x - 19y

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2 years ago

The time taken for an object to fall from a height of h m from the earth'fs surface is t s.

telo118 [61]

Answer:

B. Longer than t s,

Explanation:

Gravitational accln on earth is 9.8 m/s^2,

and one you provided as on moon is 1.6 m/s^2

that mean on moon gr. accl. is lesser!

now the time taken on earth will be lesser cuz from the same height if you drop the object from rest!

since accln on earth is higher,the object will attain higher velocity as compare to that of on moon!

✌️:)

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2 years ago

2. 3000. kg car is moving across level ground at 5.0 m/s when it begins an

gizmo_the_mogwai [7]

Answer:

yes

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2 years ago