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3 years ago

How did Newton explain why the moon did not fall to earth?

1 answer:

5 0

Newton was the once who figured out that orbits were driven by nothing more than gravity. He showed how in an orbit gravity is balanced by centrifugal force, so planets orbit the sun or the moon orbits the earth without falling. The moons momentum keeps it in a particular path rather than to fall straight down

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A stationary police car emits a sound of frequency 1240 HzHz that bounces off of a car on the highway and returns with a frequen

Tju [1.3M]

Answer

given,

frequency from Police car= 1240 Hz

frequency of sound after return = 1275 Hz

Calculating the speed of the car = ?

Using Doppler's effect formula

Frequency received by the other car

$f_1 = \dfrac{f_0(u + v)}{u}$ ..........(1)

u is the speed of sound = 340 m/s

v is the speed of the car

Frequency of the police car received

$f_2= \dfrac{f_1(u)}{u-v}$

now, inserting the value of equation (1)

$f_2= f_0\dfrac{u+v}{u-v}$

$1275=1240\times \dfrac{340+v}{340-v}$

1.02822(340 - v) = 340 + v

2.02822 v = 340 x 0.028822

2.02822 v = 9.799

v = 4.83 m/s

hence, the speed of the car is equal to v = 4.83 m/s

5 0

3 years ago

Doing aerobic exercise is most important because it

frutty [35]

Because it increases cardiorespiratory fitness and means that one has a strong heart and circulatory system. This results in being able to avoid heart disease and other dangerous diseases or disorders. Additionally, exercise can help our mental health along with maintaining weight and staying physically healthy.

3 0

3 years ago

A car drives to the east in a time of 6 hours. Then, immediately (not realistic, but just assume this is the case for this probl

garri49 [273]

Answer:

Average speed of car in the first trip is 10 km/hr

Explanation:

It is given that first the car drives 6 hours to the east

Then travels 12 km to west in 3 hours

Average speed for the entire trip = 8 km/hr

Total time = 3+6 = 9 hour

So distance traveled in 9 hour = 9×8 = 72 km

As the car travel 12 km in west so distance traveled in east = 72-12 = 60 km

Time by which car traveled in east = 6 hour

So speed $=\frac{distance}{time}=\frac{60}{6}=10km/hr$

So average speed of car in the first trip is 10 km/hr

7 0

4 years ago

Tommy was walking at a rate of 4 miles hour at noon and at 12:30 pm he was walking at a brisk rate of 6 miles hour . Two hours l

maks197457 [2]

Answer:

B) Tommy had a positive acceleration between noon and 12:30 pm.

Explanation:

Acceleration is defined as the rate of change of velocity:

$a=\frac{v-u}{t}$

where

v is the final velocity

u is the initial velocity

t is the time

In the problem,

- At noon, Tommy is walking at a velocity of 4 mi/h

- At 12.30 pm, Tommy is walking at a velocity of 6 mi/h

- A time of half an hour (0.5 h) passed between the two moments

So Tommy's acceleration is

$a=\frac{6 mi/h-4 mi/h}{0.5 h}=4 mi/h^2$

and the acceleration is positive, since the velocity has increased.

3 0

3 years ago

Read 2 more answers

A stone is dropped from a tower 100 meters above the ground. The stone falls past ground level and into a well. It hits the wate

ELEN [110]

A useful formula that gives the free-fall distance from rest in 'T' seconds:

   D = (1/2 G) x (T²)

      G = 9.81 m/s²
1/2 G = 4.905 m/s²

   D (5 seconds) = (4.905 m/s²) x (5 sec)²

      = (4.905 m/s²) x (25 sec²)

      =    122.625 meters .

Since the tower-top is 100m above ground,
the depth of the well, to the top of the water,
accounts for the additional 22.625 meters.

My question is: How do you know exactly when the stone hit the water ?

You probably stood at the top of the well and listened for the
sound of the 'plop'. But it took some time after the stone hit
the water for the sound of the plop to come back up to you.
Well, can't you just subtract that time ? Yes, but you need
to know how much time to subtract. That depends on the
depth of the well ... which is exactly what you're trying to
determine, so you don't know it yet.

Oh well. That's a deep subject.

7 0

3 years ago