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3 years ago

15

During a race, a runner runs at a speed of 6 m/s. 2 seconds later, she is running at a speed of 10 m/s. What is the runner’s acc

eleration? Show your work.

1 answer:

Lina20 [59]3 years ago

6 0

V o = 6 m/s,
t = 2 s
v = 10 m/s
v = v o + a t
a t = v - v o
a = ( v - v o ) / t
a = ( 10 m/s - 6 m/s ) / 2 s = 4 m/s / 2 s = 2 m/s²
Answer:
The runner`s acceleration is 2 m/s².

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With the temperature held constant, the piston of a cylinder containing a gas is pulled out so that the volume increases from 0.

klio [65]

Answer:

P1 = 240 kPa.

Explanation:

Given the following data;

Initial volume = 0.3 m³

Final volume, V2 = 0.9 m³

Final pressure, P2 = 80 kPa

To find the initial pressure, we would use Boyle's law;

Boyles states that when the temperature of an ideal gas is kept constant, the pressure of the gas is inversely proportional to the volume occupied by the gas.

Mathematically, Boyles law is given by the formula;

$PV = K$

$P_{1}V_{1} = P_{2}V_{2}$

Substituting into the formula, we have;

$P_{1} * 0.3 = 80 * 0.9$

$0.3P_{1} = 72$

$P_{1} = \frac {72}{0.3}$

$P_{1} = 240$

Therefore, the initial pressure of the gas is 240 kPa

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3 years ago

Q|C The speed of a one-dimensional compressional wave traveling along a thin copper rod is 3.56 km/s . The rod is given a sharp

Gekata [30.6K]

The length of rod in terms v(r) and t is L = [ Δt / (1/343) - (1/v(r)) ].

3.56 km/s is the speed of a one-dimensional compressional wave moving along a thin copper rod.

At one end of the rod, a hard hammer strike is delivered. With a time interval of Δt between the two pulses, a listener at the other end of the rod hears the sound twice as it travels through the metal and the air.

The time interval is given by t = L/v.

The delay between pulses arrivals is:

Δt = L [(1/v(air)) - (1/v(copper))]

Now,

When the copper rod is swapped out for a different substance and the sound speed is measured as v(r).

The speed of air, v(air) = 343 m/s

Then,

L = [ Δt / (1/v(air)) - (1/v(r)) ]

L = [ Δt / (1/343) - (1/v(r)) ]

Here L is the length of the rod, Δt is in seconds and v(r) is the speed of sound in the rod.

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1 year ago

Cobaltâ’60 is a radioactive isotope used to treat cancers of the brain and other tissues. A gamma ray emitted by an atom of this

Crank

Energy of gamma rays is given by equation

$E = h\nu$

here we know that

h = Planck's constant

$\nu = frequency$

now energy is given as

$E = 4.70 MeV = 4.70 \times 10^6 \times 1.6 \times 10^{-19}$

$E = 7.52 \times 10^{-13} J$

now by above equation

$E = h\nu$

$7.52 \times 10^{-13} = 6.6 \times 10^{-34} \nu$

$\nu = 1.14 \times 10^{21} Hz$

now for wavelength we can say

$\lambda = \frac{c}{\nu}$

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3 years ago

What is a measure between the difference in start and end positions?

crimeas [40]

Answer:

Displacement

General Formulas and Concepts:

<u>Kinematics</u>

Displacement vs Total Distance

Explanation:

Displacement is the difference between the start position and end position.

Total Distance is the entire distance <em>traveled</em> between the start and end position.

Topic: AP Physics 1 Algebra-Based

Unit: Kinematics

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3 years ago

What is the speaker’s power output if the sound intensity level is 102 dBdB at a distance of 25 mm ? Express your answer to two

lesya [120]

Answer:

Power = 124.50 W

Explanation:

Given that:

The Sound intensity of a speaker output is 102 dB

and the distance r = 25 m

For the intensity of sound,

$\beta (dB)= 10 \ log_{10 } (\dfrac{I}{I_o})$

where;

the threshold of hearing $I_o = 10^{-12} (W/m^2)$

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$10^{10.2} = \dfrac{I}{10^{-12}}$

$I = 10^{10.2} \times 10^{-12}$

I = 0.01585 W/m²

If we recall, we know remember that ;

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Power = 124.50 W

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3 years ago