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2 years ago

Which of the following statements is true?

Physics

1 answer:

9966 [12]2 years ago

5 0

Answer:

c) the distance a star is from Earth affects how bright it appears in the night sky.

Explanation:

a) there are MUCH bigger stars in the universe then the sun. The sun is said to be a medium star.

b) If the sun were to burn out it would affect earth a lot. The sun is needed for Earth's survival. Earth needs the heat from the sun or it'd a big cold planet full of ice that probably couldn't support life.

d) the big bang theory supports that the universe is growing

I know c), is correct

You might be interested in

Label the sound wave- amplitude, wavelength, crest, trough

enot [183]

Answer:

A - Crest, B - amplitude, C - wavelength, D - trough

Explanation:

7 0

2 years ago

Each driver has mass 79.0 kg. Including the masses of the drivers, the total masses of the vehicles are 800 kg for the car and 4

Mademuasel [1]

Answer:

Force exerted on the car driver by the seatbelt = 8139.4 N = 8.14 kN

Force exerted on the truck driver by the seatbelt = 1628.2 N = 1.63 kN

It is evident that the driver of the smaller vehicle has it worse. The car driver is in way more danger in this perfectly inelastic head-on collision with a bigger vehicle (the truck).

Explanation:

First of, we calculate the velocity of the vehicles after collision using the law of conservation of Momentum

Momentum before collision = Momentum after collision

Since the collision of the two vehicles was described as a head-on collision, for the sake of consistent convention, we will take the direction of the velocity of the bigger vehicle (the truck) as the positive direction and the direction of the car's velocity automatically is the negative direction.

Velocity of the truck before collision = 6.80 m/s

Velocity of the car before collision = -6.80 m/s

Let the velocity of the inelastic unit of vehicles after collision be v

Momentum before collision = (4000)(6.80) + (800)(-6.80) = 27200 - 5440 = 21,760 kgm/s

Momentum after collision = (4000 + 800)(v) = (4800v) kgm/s

Momentum before collision = Momentum after collision

21760 = 4800v

v = (21760/4800)

v = 4.533 m/s (in the direction of the big vehicle (the truck)

So, we then apply Newton's second law of motion which explains that the magnitude change in momentum is equal to the magnitude of impulse.

|Impulse| = |Change in momentum|

But Impulse = (Force exerted on each driver by the seatbelt) × (collision time) = (F×t)

Change in momentum = (Momentum after collision) - (Momentum before collision)

So, for the driver of the truck

Initial velocity = 6.80 m/s (the driver moves with the velocity of the truck)

Final velocity = 4.533 m/s

Change in momentum of the truck driver = (79)(6.80) - (79)(4.533) = 179.1 kgm/s

(F×t) = 179.1

F × 0.110 = 179.1

F = (179.1/0.11)

F = 1628.2 N = 1.63 kN

So, for the driver of the car

Initial velocity = -6.80 m/s (the driver moves with the velocity of the car)

Final velocity = 4.533 m/s

Change in momentum of the car driver = (79)(-6.80) - (79)(4.533) = -895.3 kgm/s

(F×t) = |-895.3|

F × 0.110 = 895.3

F = (895.3/0.11)

F = 8139.4 N = 8.14 kN

Hope this Helps!!!

3 0

3 years ago

A harmonic wave on a string with a mass per unit length of 0.050 kg/m and a tension of 60 N has an amplitude of 5.0 cm. Each sec

Dennis_Churaev [7]

Answer:

Power of the string wave will be equal to 5.464 watt

Explanation:

We have given mass per unit length is 0.050 kg/m

Tension in the string T = 60 N

Amplitude of the wave A = 5 cm = 0.05 m

Frequency f = 8 Hz

So angular frequency $\omega =2\pi f=2\times 3.14\times 8=50.24rad/sec$

Velocity of the string wave is equal to $v=\sqrt{\frac{T}{\mu }}=\sqrt{\frac{60}{0.050}}=34.641m/sec$

Power of wave propagation is equal to $P=\frac{1}{2}\mu \omega ^2vA^2=\frac{1}{2}\times 0.050\times 50.24^2\times 34.641\times 0.05^2=5.464watt$

So power of the wave will be equal to 5.464 watt

6 0

2 years ago

A book is sliding along a desk top. Because the book is in motion ,you know that the forces acting on the book are A. Balanced B

Virty [35]

Just because the book is moving doesn't tell you anything about the forces on it, or even whether there ARE any.

Just look at Newton's first law of motion, and this time, let's try and THINK about it too. It says something to the effect that any object continues in constant, uniform MOTION ..... UNLESS acted on by an external force.

4 0

3 years ago

A hot-air balloon is floating above a straight road. To estimate their height above the ground, the balloonists simultaneously m

Karolina [17]

Answer:

3.1 miles

Explanation:

To solve this question it is important to remember that the distance between two mile markers is approximately 1 mile

Once this is known, the question becomes very easy to solve. We make two triangle, which have the following three points

Triangle 1: Hot-Air-Balloon, Ground, Milepost 1 - With angle of depression 20

Triangle 2: Hot-Air-Balloon, Ground, Milepost 2 - With angle of depression 18

As a reminder, the angle of depression is simply the angle the balloonist's head makes with the horizontal plane to be able to see the milepost.

From this we can simply drive two formulas using the Tan function

Equation 1 - $Tan(90-18) = \frac{b+1}{h}$

Equation 2 - $Tan(90-20) = \frac{b}{h}$

Solving them simultaneously we get the value of height (h) to be 3.0852 miles or 3.1 miles

8 0

3 years ago