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2 years ago

Why are you able to observe the Doppler Effect with sound waves on Earth but not light waves?

1 answer:

4 0

The doppler effect is when waves’ wavelengths get squished when the source is moving toward you or stretched when the source is moving away from you. it can be observed with sound waves but not light waves because the speed of light is just too fast, meaning that we can’t move toward or away fast enough. (also some stuff with relativity).

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The cheetah can maintain its maximum speed for only 7.5 s. What is the minimum distance the gazelle must be ahead of the cheetah

amm1812

Basically the cheetah is running 31.5km/h faster than the gazelle. So to determone how long it will take to cover 9mm at that speed, you have to a lot of work. If you skip all of that work, the answer is 1.60m seconds

6 0

3 years ago

At a point between the earth and the moon, the magnitude of the force exerted on an object by the earth's gravity equals the mag

S_A_V [24]

1.62 m/s is the correct answer to the problem

8 0

3 years ago

The velocity of an object is the distance it travels per unit time. Suppose the velocity of a gilding bird is measured to be 52.

Elanso [62]

Answer:

$d=7.115s$

Explanation:

What problem says can be written mathematically as:

$v=\frac{d}{t}$

Where:

$v=Velocity\\t=Time\\d=Distance$

The problem itself it's really simple, we only need to replace the data provided in the previous equation, but first, let's convert the units of the velocity from cm/s to m/s because we have to work with the same units and working in meters is the most apropiate action, because is the base unit of length in the International System of Units:

$52\frac{cm}{s} *\frac{1m}{100cm} =0.52\frac{m}{s}$

Now, we can replace the data in the equation and find the time it will take the bird to travel 3.7 m:

$0.52=\frac{3.7}{t}$

Solving for t, multiplying by t both sides, and dividing by 0.52 both sides:

$t=\frac{3.7}{0.52} =7.115384615s\approx7.115s$

5 0

3 years ago

A measure of how far an object has moved from a starting point

Anvisha [2.4K]

Volume??? velocity??????

5 0

3 years ago

A tennis ball is a hollow sphere with a thin wall. It is set rolling without slipping at 4.03 m/s on the horizontal section of a

seraphim [82]

Answer:

2.38 m/s, 4.31 m/s, lower

Explanation:

Initial energy = final energy

½ m v₀² + ½ I ω₀² = mgh + ½ m v₁² + ½ I ω₁²

Since the ball is rolling without slipping, ω = v / r.

For a hollow sphere, I = ⅔ m r².

½ m v₀² + ½ (⅔ m r²) (v₀ / r)² = mgh + ½ m v₁² + ½ (⅔ m r²) (v₁ / r)²

½ m v₀² + ⅓ m v₀² = mgh + ½ m v₁² + ⅓ m v₁²

⅚ m v₀² = mgh + ⅚ m v₁²

⅚ v₀² = gh + ⅚ v₁²

v₀² = 1.2gh + v₁²

v₁ = √(v₀² − 1.2gh)

Given v₀ = 4.03 m/s, g = 9.80 m/s, h = 0.900 m:

v₁ = √((4.03)² − 1.2 (9.80) (0.900))

v₁ ≈ 2.38 m/s

At the top of the loop, the sum of the forces in the radial direction is:

∑F = ma

W + N = m v² / R

N = m v² / R - mg

N = m (v² / R - g)

Given v = 2.38 m/s, R = 0.450 m, and g = 9.80 m/s²:

N = m ((2.38)² / 0.450 - 9.80)

N = 2.77m

N ≥ 0, so the ball stays on the track.

Initial energy = final energy

Borrowing from part a):

v₂ = √(v₀² − 1.2gh)

This time, h = -0.200 m:

v₂ = √((4.03)² − 1.2 (9.80) (-0.200))

v₂ ≈ 4.31 m/s

Without the rotational energy:

½ m v₀² = mgh + ½ m v₁²

½ v₀² = gh + ½ v₁²

v₀² = 2gh + v₁²

v₁ = √(v₀² - 2gh)

This is less than v₁ we calculated earlier.

6 0

3 years ago