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3 years ago

Question 9 of 10 Which of the following is a scalar quantity? O

Physics

2 answers:

vekshin13 years ago

5 0

Answer:

work is scalar qualit y

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Reil [10]3 years ago

3 0

Answer:

(D) is the scalar quantity because unlike the other choices, no direction is attached to its magnitude.

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A satellite in the shape of a solid sphere of mass 1,900 kg and radius 4.6 m is spinning about an axis through its center of mas

konstantin123 [22]

Answer:

Therefore, the new rotation rate of the satellite is 6.3 rev/s.

Explanation:

The expression for conservation of the angular momentum (L) is

$L_{i} = L_{f} I_{i}\times\omega_{i} = I_{f}\times\omega_{f}$

Where

$I_{i}\ and \ \omega_{i}$ initial moment of inertia and angular velocity

$I_{f}\ and \ \omega_{f}$ is the final moment of inertia and angular velocity

The expression of moment of inertia of the satellite (a solid sphere) is

$I_{i} = \frac{2}{5}m_{s}r^{2}$

Where $m_{s}$ is the satellite mass

r is the radus of the sphere

Substititute 1900kg for m and 4.6m for r

$I_{i} = \frac{2}{5}m_{s}r^{2}\\\\ = \frac{2}{5}\times1900 kg\times (4.6 m)^{2} \\\\= 1.61 \cdot 10^{4} kgm^{2}$

The final moment of inertia of the satellite about the centre of mass

$I_{f} = I_{i} + 2\timesI_{x} \\\\= 1.61 \cdot 10^{4} kgm^{2} + 2\times\frac{1}{3}m_{x}l^{2}$

Where $m_{x}$ is the antenna's mass and

I is the length of the antenna

$I_{f} = 1.61 \cdot 10^{4} kgm^{2} + 2\times\frac{1}{3}150.0 kg\times(6.6 m)^{2} \\\\= 2.05 \cdot 10^{4} kgm^{2}$

So, the Final rotation rate of the satellite is:

$I_{i}\times\omega_{i} = I_{f}\times\omega_{f} \\\\\omega_{f} = \frac{I_{i}\times\omega_{i}}{I_{f}} \\\\= \frac{1.61 \cdot 10^{4} kgm^{2}\times8.0 \frac{rev}{s}}{2.05 \cdot 10^{4} kgm^{2}} \\\\= 6.3 rev/s$

Therefore, the new rotation rate of the satellite is 6.3 rev/s.

5 0

3 years ago

A solid ball and a hollow ball, each with a mass of 1.00 kg and radius of 0.100 m start from rest and roll down a ramp of length

nordsb [41]

Answer:

The solid ball and hollow ball both will reach the bottom with the same speed.

Explanation:

The speed of the solid and hollow balls is independent of the mass and the radius. A solid and hollow ball experience same speed on a given incline.

The speed can be calculated as

v = √(10/7)gh

where g is gravitational acceleration and h is the height

sinθ = h/L

h = L*sinθ

h = 3*sin(35)

h = 1.72 m

v = √(10/7)*9.8*1.72

v = 4.91 m/s

Both balls will reach the bottom at the speed of 4.91 m/s.

8 0

3 years ago

In your own words, explain how Doppler radar works. Describe the properties of electromagnetic waves and interactions that make

lisov135 [29]

If you stand up in a big room and echo, your voice will echo from the walls. As long as the room is empty. Since the speed of sound is constant, depending on air density, the more humid the air the faster and farther sound travels. The speed of sound is constant, you could measure the time it takes for your voice to echo off the walls. The same thing happens with Doppler radar, but it’s not voice, it has higher frequency signals.<span> </span>

6 0

2 years ago

Read 2 more answers

THIS IS SCIENCE .What is most likely to happen during weathering? Moving of sediment Breaking down of rocks Laying down of sedim

MaRussiya [10]

The answer is B. Breaking down of rocks.

7 0

3 years ago

A screen is placed a distance dd to the right of an object. A converging lens with focal length ff is placed between the object

Elina [12.6K]

Answer:

Explanation:

The formula for the object - image relationship of thin lens is given as;

1/s + 1/s' = 1/f

Where;

s is object distance from lens

s' is the image distance from the lens

f is the focal length of the lens

Total distance of the object and image from the lens is given as;

d = s + s'

We earlier said that; 1/s + 1/s' = 1/f

Making s' the subject, we have;

s' = sf/(s - f)

Since d = s + s'

Thus;

d = s + (sf/(s - f))

Expanding this, we have;

d = s²/(s - f)

The derivative of this with respect to d gives;

d(d(s))/ds = (2s/(s - f)) - s²/(s - f)²

Equating to zero, we have;

(2s/(s - f)) - s²/(s - f)² = 0

(2s/(s - f)) = s²/(s - f)²

Thus;

2s = s²/(s - f)

s² = 2s(s - f)

s² = 2s² - 2sf

2s² - s² = 2sf

s² = 2sf

s = 2f

8 0

3 years ago