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nikitadnepr [17]
3 years ago
6

A football is kicked into the air with a velocity of 32m/s at an angle of 25º. At the very top of the ball’s path, its vertical

velocity is
Physics
1 answer:
Travka [436]3 years ago
7 0
At the "very top" of the ball's path, there's a tiny instant when the ball
is changing from "going up" to "going down".  At that exact tiny instant,
its vertical speed is zero.

You can't go from "rising" to "falling" without passing through "zero vertical
speed", at least for an instant.  It makes sense, and it feels right, but that's
not good enough in real Math.  There's a big, serious, important formal law
in Calculus that says it.  I think Newton may have been the one to prove it,
and it's named for him.

By the way ... it doesn't matter what the football's launch angle was,
or how hard it was kicked, or what its speed was off the punter's toe,
or how high it went, or what color it is, or who it belongs to, or even
whether it's full to the correct regulation air pressure.  Its vertical speed
is still zero at the very top of its path, as it's turning around and starting
to fall.
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joja [24]

Answer:

5.25\cdot 10^{40} kg m^2/s

Explanation:

The angular momentum of the pulsar is given by:

L=m\omega r^2

where

m=2.8\cdot 10^{30} kg is the mass of the pulsar

r = 10.0 km = 1\cdot 10^4 m is the radius

\omega is the angular speed

Given the period of the pulsar, T=33.5\cdot 10^{-3} s, the angular speed is given by

\omega=\frac{2\pi}{T}=\frac{2 \pi}{33.5\cdot 10^{-3}s}=187.5 rad/s

And so, the angular momentum is

L=m\omega r^2=(2.8\cdot 10^{30}kg)(187.5 rad/s)(1\cdot 10^4 m)^2=5.25\cdot 10^{40} kg m^2/s

8 0
3 years ago
If a star is 720 , 000 , 000 , 000 , 000 meters from Earth, how many seconds does it take light to travel from the Earth to the
Minchanka [31]

Answer:

anywhere between 100000 to about 400000 human years .

Explanation:

5 0
2 years ago
Suppose the ski patrol lowers a rescue sled carrying an injured skier, with a combined mass of 97.5 kg, down a 60.0-degree slope
Kitty [74]

a. 1337.3 J work, in joules, is done by friction as the sled moved 28 m along the hill.

b.21,835 J work, in joules, is done by the rope on the sled this distance.

c. 23,170 J   the work, in joules done by the gravitational force on the sled d. The net work done on the sled, in joules is 43,670 J.

       

<h3>What is friction work?</h3>

The work done by friction is the force of friction times the distance traveled times the cosine of the angle between the friction force and displacement

a. How much work is done by friction as the sled moves 28m along the hill?

ans. We use the formula:

friction work = -µ.mg.dcosθ

  = -0.100 * 97.5 kg * 9.8 m/s² * 28 m * cos 60

= -1337.3 J

-1337.3 J work, in joules, is done by friction as the sled moved 28 m along the hill.

b. How much work is done by the rope on the sled in this distance?

We use the formula:

Rope work = -m.g.d(sinθ - µcosθ)

rope work = - 97.5 kg * 9.8 m/s² * 28 m (sin 60 – 0.100 * cos 60)

                     = 26,754 (0.816)

                     = 21,835 J

21,835 J work, in joules, is done by the rope on the sled this distance.

c.  What is the work done by the gravitational force on the sled?

By using  the formula:

Gravity work = mgdsinθ

                    = 97.5 kg * 9.8 m/s² * 28 m * sin 60

                    = 23,170 J

23,170 J   the work, in joules done by the gravitational force on the sled .

       

D. What is the total work done?

By adding all the values

work done =  -1337.3 + 21,835 + 23,170

                 = 43,670 J

The net work done on the sled, in joules is 43,670 J.

Learn more about friction work here:

brainly.com/question/14619763

#SPJ1

4 0
2 years ago
While driving a 2150 kg car, carl steps on the gas pedal, accelerating at 4.0 m/s2. If the coefficient of friction between his c
Mrac [35]

Answer:

d. 3332.5 [N]

Explanation:

To solve this problem we will use newton's second law, which tells us that the sum of forces is equal to the product of mass by acceleration.

Here we have two forces, the force that pushes the car to move forward and the friction force.

The friction force is equal to the product of the normal force by the coefficient of friction.

f = N * μ

f = (m*g) * μ

where:

N = weight of the car = 2150*9.81 = 21091.5 [N]

μ = 0.25

f = (21091.5) * 0.25

f = 5273 [N]

Now as the car is moving forward, the car wheels move clockwise. The friction force between the wheels of the car and the pavement must be counterclockwise, i.e. counterclockwise. Therefore the direction of this force is forward. This way we have:

F + f = m*a

F + 5273 = 2150*4

F = 8600 - 5273

F = 3327 [N]

Therefore the answer is d.

6 0
3 years ago
Two atoms each contain 6 protons, but one has 6 neutrons and the other has 8 neutrons. What are these atoms called? A. ions B. r
ki77a [65]

Answer:

These atomos are called isotopes.

Explanation:

Each chemical element is characterized by the number of protons in its nucleus, which is called the atomic number (Z).

The number of neutrons in the nucleus can vary. There are almost always as many or more neutrons than protons. The atomic mass (A) is obtained by adding the number of protons and neutrons in a given nucleus.

The same chemical element can be made up of different atoms, that is, their atomic numbers are the same, but the number of neutrons is different. These atoms are called isotopes of the element. That is, isotopes are atoms whose atomic nuclei have the same number of protons but different numbers of neutrons.

So, <u><em>these atomos are called isotopes.</em></u>

3 0
3 years ago
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