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Zielflug [23.3K]
3 years ago
7

Physical Science Pre-Test 2020-2021 Question: 1-10 The distance between Earth and the Moon was determined by measuring the time

it took for light waves from Earth to travel to the Moon and back. Why was it not possible to use sound waves for this experiment Sound waves must move through a substance Sound waves would change frequency on the return to Earth Sound waves move too slowly for the technique to be accurate Sound waves move more slowly in Earth's atmosphere than in space​
Physics
1 answer:
LiRa [457]3 years ago
5 0

Answer:

Option A - Sound waves must move through a substance

Explanation:

Unlike light waves, sound waves must travel through a medium/substance for such a medium to vibrate and then produce sound.

As a matter of fact sound can't travel through empty space.

Thus, looking at the options given, the correct one is:

Sound waves must move through a substance which is Option A

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The height of a circular tower is 179 meters and its diameter is 48 meters. (Assume that the building is a perfect cylinder). Wh
EastWind [94]

The definition of a scale of 1: 166 will mean that the scale of 1 in the model will be equivalent to 166 times the measurement in the real model, therefore we will have that the height would be 166 times smaller than the 179m given:

h = \frac{179m}{166} = 1.078m = 107.8cm

The same for the diameter,

\phi = \frac{48m}{166}= 0.2891m = 28.91cm

The volume of a cylinder is given as

V = (\pi r^2)(h)

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If an object has a mass of 8 kg, what is its approximate weight on Earth?
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2 years ago
You and a friend each hold a lump of wet clay. Each lump has a mass of 25 grams. You each toss your lump of clay into the air, w
solniwko [45]

Answer:

a) p(total) = <0.05, 0.1, 0.1 > kg m/s

b) p = <0.05, 0.1, 0.1 > kg.m/s

c) v_f = < 1, 2, 2 > m/s

Explanation:

a.)

Mass of each lump = 25 g = 0.025 kg

Velocity of lump 1 = < -2, 0, -7 > m/s

Momentum of lump 1 = Mass×Velocity

                                   = 0.025×< -2, 0, -7 >

                                   = < -0.05, 0, 0.175> kg m/s

Velocity of lump 2 = < 4, 4, -3 > m/s

Momentum of lump 2 = Mass×Velocity

                                    = 0.025×< 4, 4, -3 >

                                    = < 0.1, 0.1, -0.075> kg m/s

Total momentum before impact  =  < -0.05,  0,  0.175 > + < 0.1, 0.1, -0.075>

                                                      = < 0.05, 0.1, 0.1 > kg m/s

⇒p(total) = <0.05, 0.1, 0.1 > kg m/s

b)

As we know that,

By the law of conservation of linear momentum,

The total momentum will be the same before and after the collision.

⇒Momentum of the stuck together  after the collision = Total momentum of the lumps just before impact.

⇒ p = <0.05, 0.1, 0.1 > kg m/s

c)

Let the final velocity =  v_f

Total mass = 0.025 + 0.025 = 0.05 kg

As

Momentum = mass ×velocity

⇒ <0.05, 0.1, 0.1 > = 0.05 ×v_f

⇒ v_f = <0.05, 0.1, 0.1 > / 0.05

          = < 1, 2, 2 > m/s

⇒v_f = < 1, 2, 2 > m/s

7 0
2 years ago
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