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lidiya [134]
3 years ago
5

While skateboarding at 19 km/h, Alana throws a tennis ball at 11 km/h to her friend Oliver. If Alana is the reference frame, the

speed of the tennis ball is
Physics
2 answers:
ANTONII [103]3 years ago
5 0

Well, you see, I don't think Alana really is the reference frame. 
Call me paranoid, but I think you changed the reference frame
during the question, and didn't tell us.

In which reference frame is the 19 km/hr measured ?
It CAN'T be Alana's reference frame.  Your own reference
frame moves along with you, and you can't move in it, even
if your name is Alana.

If Alana is the reference frame, and she throws the tennis ball
at 11 km/hr, then the speed of the ball is 11 km/hr in Alana's
reference frame.  Her reference frame moves with  her, so
it makes no difference how fast she is skateboarding in any
other reference frame, who she throws the ball at, or whether
or not he sees it coming and catches it.

Yes, this stuff can get confusing.  And if you think it's bad now,
wait till you start reading some of Prof. Einstein's stuff, where
two people in the same reference frame can watch the same
tennis ball, and not even agree on how fast it's moving, because
THEY're both moving and their own motion makes their rulers
and clocks change !  So they measure different speeds, and
they're both right !

But I got distracted.  I'm sorry.  The point I'm trying to make,
right now when you're just starting to learn reference frames,
is that EVERY time you say a speed, you have to tell which
reference frame the speed is in.  Because, as you're starting
to learn, the same object can have a different speed in every
reference frame.

And, just in case you're thinking about this later today
and you want to ask "Which one is the REAL speed  ?" . . .
THAT's the whole point of learning about reference frames !
There is NO SUCH THING as REAL speed.  It ALWAYS
depends on which reference frame it's measured in.  They're
all different, they're all real, and they're all correct.

makvit [3.9K]3 years ago
3 0

The first thing we must do for this case is to define a frame of reference.

We know that, the frame of reference for this case is Alana.

Therefore, the tennis ball has a speed relative to Alana.

The speed relative to Alana, is the same speed with which Alana throws the tennis ball.

Therefore, the speed of the tennis ball is:

v = 11 Km/h

Answer:

The speed of the tennis ball is:

v = 11 Km/h

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An unlit match is held near (not touching) a Bunsen flame. The match doesn't get hot enough to light because
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The answer is option D)
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3 years ago
Location C is 0.02 m from a small sphere which has a charge of 3 nanocoulombs uniformly distributed on its surface. Location D i
kkurt [141]

The change in potential along a path from C to D due to a small charged sphere is 900 V.

Given:

Charge, Q = 3 nC = 3 × 10⁻⁹ C

Distance between the sphere and point C, r₁ = 0.02 m

Distance between the sphere and point D, r₂ = 0.06 m

Calculation:

We know that the electric potential is given as:

V = k Q/r   - (1)

where, V is the electric potential

            k is Coulomb's force constant

            Qis the charge on the  sphere

            r is the  separation distance

The electric potential at point C due to charged sphere can be given as:

V₁ = k Q/r₁

   = (9×10⁹ Nm²/C²) [(3 × 10⁻⁹ C)/(0.02 m)]

   = 1350 V

The electric potential at point D due to charged sphere can be given as:

V₂ = k Q/r₂

   = (9×10⁹ Nm²/C²) [(3 × 10⁻⁹ C)/(0.06 m)]

   = 450 V

Now, the change in potential along the path from C to D can be calculated as:

ΔV = V₂ - V₁

     = 450 V - 1350 V

     = -900 V

The negative sign indicates that the work is done against the electric field in moving the charge from C to D.

Therefore, the change in potential along a path from C to D is 900 V against the direction of the electric field.

Learn more about the electric potential here:

<u>brainly.com/question/12645463</u>

#SPJ4

8 0
1 year ago
Read 2 more answers
Based on its type of chemical bond, which of the following has the highest boiling point?
Sever21 [200]
<h3><u>Answer;</u></h3>

Potassium chloride

<h3><u>Explanation;</u></h3>
  • Potassium Chloride is an ionic compound and has ionic bond which is stronger than covalent bond in ethyl alcohol,water ,ammonia, and thus has the highest boiling point .
  • ionic bond is a type of bond that results from the transfer of electrons between metallic atoms and non-metallic atoms.
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The force of gravitation between two spherical bodies is Gm1 m2 /r2, where r is separation between their dash
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Explanation:

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6 0
3 years ago
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An electron is released a short distance above earth's surface. a second electron directly below it exerts an electrostatic forc
slamgirl [31]

The mass of an electron is 9.109 x 10⁻³¹ kg

The weight of the electron is (mass) x (g) =  8.926 x 10⁻³⁰ Newton

The charge on an electron is -1.602 x 10⁻¹⁹ Coulomb

The repelling force between the two electrons is (K · q₁ · q₂ / r²) =

(8.98755 x 10⁹ N-m²/C²) x (1.602 x 10⁻¹⁹ C)² / D²

In order for the bottom one to just exactly hold the top one up at a distance 'D', the repelling force has to be exactly equal to the weight of the upper electron.

8.926 x 10⁻³⁰ N = (8.98755 x 10⁹ N-m²/C²)·(1.602 x 10⁻¹⁹ C)² / D²

We have to solve THAT ugly mess for ' D '.

Clean up the units first:

Cancel the C² on the right side, then divide each side by Newton:

8.926 x 10⁻³⁰ = (8.98755 x 10⁹ m²) x (1.602 x 10⁻¹⁹)² / D²

Now, let's multiply both sides by (D² x 10²⁹) :

D² x 8.926 x 10⁻¹ = (8.98755 m²) x (1.602)²

Divide each side by (0.8926):

D² = (8.98755 x 1.602²) / (0.8926)  meter²

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Take the square root of each side:

<em>D = 5.08 meters</em>

I am shocked, impressed, and amazed !

Are you shocked, impressed, or amazed ?

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