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3 years ago

Which statement best explains why sound waves cannot travel through space

1 answer:

6 0

The vacuum of outer space has essentially zero air. Because sound is just vibrating air, space has no air to vibrate and therefore no sound. If you are sitting in a space ship and another space ship explodes, you would hear nothing. So, in order for sound to travel, there has to be something with molecules for it to travel through. On Earth, sound travels to your ears by vibrating air molecules. In deep space, the large empty areas between stars and planets, there are no molecules to vibrate. There is no sound there.

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zanele has a mass of 40kg and is sitting inside a 20kg cart .zanele's friends pull a cart with a force of 500N at an angle of 20

Dmitriy789 [7]

The net horizontal force acting on the cart is 169.85 N.

The change in the carts momentum is 5,000 Ns.

The net horizontal force on Zanele is same as the net horizontal force on the cart.

If angle between the 500N force and the horizontal is decreased, the final velocity of the cart increases.

The given parameters:

Mass of zanele, m1 = 40 kg
Mass of the cart, m2 = 20 kg
Applied force, F = 500 N, at angle 20 degrees
Frictional force on the cart, Ff = 300 N
Time, t = 10 s

<h3>Net horizontal force on the cart;</h3>

The net horizontal force acting on the cart is calculated as follows;

$F_{net} = F - F_f\\\\F_{net} = 500 \times cos(20) - 300\\\\F_{net} = 169.85 \ N$

<h3>Change in momentum;</h3>

The change in the carts momentum at the given time of applied force is calculated as follows;

$\Delta mv = Ft \\\\\Delta mv = 500 \times 10= 5,000 \ Ns$

The net horizontal force on Zanele is same as the net horizontal force on the cart.

<h3>The final velocity of the cart;</h3>

When the angle decreases the cart's final velocity would be affected as follows;

$F_{net} = F - F_f\\\\F_{net} = \frac{mv}{t} \\\\\frac{mv}{t} = F - F_f\\\\ \frac{mv}{t} = Fcos(\theta) - F_f\\\\let \ \theta = 0^0\\\\\frac{mv}{t} =500 \times cos(0) - 300\\\\\frac{mv}{t} = 200\\\\v = \frac{200 t}{m} \\\\when \ \theta = 20^0\\\\\frac{mv}{t} =500 \times cos(20) - 300\\\\\frac{mv}{t} = 169.85\\\\v = \frac{169.85t}{m}$

Thus, if angle between the 500N force and the horizontal is decreased, the final velocity of the cart increases.

Learn more about net horizontal force here: brainly.com/question/21684583

5 0

3 years ago

Which of these statements is correct about photosynthesis and decomposition?

Ede4ka [16]

<span>The last option. Plants absorb carbon dioxide from the atmosphere, water from the soil and other nutrients also from the soil - salts containing nitrogene, potassium, sulphur, etc. They use water and carbon dioxide to produce sugar through photosyntesis. Decomposition is the reaction that converts any organic compound back into inorganic compounds - water, carbon dioxide and salts containing nitrogene, potassium, sulphur, etc. So it's basically the opposite. So photosyntesis uses carbon dioxide as a reactive and take it from the atmosphere, whereas decomposition generates carbon dioxide as a product and releases it to the atmosphere.</span>

7 0

4 years ago

Find h , the maximum height attained by the projectile. express the maximum height in terms of v 0 , Î¸ , and g .

lutik1710 [3]

solution:

the utmost height would be comprehensive while y'(t)=0. (on the suitable of the trajectory, the y speed is 0.) $y(t)=(88sin20)t-16t^2 y'(t)=88sin20-32t So y'(t)=0 while t=(88sin20)/32$

3 0

4 years ago

One kilowatt-hour (kWh) is the amount of work or energy generated when one kilowatt of power is supplied for a time of one hour.

Helga [31]

Answer:

The energy in one kilowatt-hour is $36\times10^{5}\ J$

Explanation:

Given that,

Power = 1 kW

Time = 1 hour

One kilowatt-hour (kWh) is the amount of work or energy generated when one kilowatt of power is supplied for a time of one hour

We need to calculate the energy

Using formula of energy

$E=p\times t$

Where, P = power

t = time

Put the value into the formula

$E=1\times10^{3}\times3600$

$E=36\times10^{5}\ J$

Hence, The energy in one kilowatt-hour is $36\times10^{5}\ J$

6 0

4 years ago

Siska hit a golf ball into the air with an initial velocity of 56 feet per second. The height h in feet of the ball above the gr

olasank [31]

To find the time it takes for the ball to reach the given height, we need an equation that relates the height and time it travel which is given to be <span>h=-16t^{2}+56t. We just substitute the height of 49 feet then solve for t. We do as follows:

</span><span>h=-16t^{2}+56t
49 = </span>-16t^{2}+56t
t = 1.75 seconds

Hope this answers the question. Have a nice day.

4 0

3 years ago

Read 2 more answers