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2 years ago

10

Last year a baseball player made 63 errors. This year he made 42. What percent decrease was there in the number of errors commit

ted by the baseball player?

1 answer:

Crank2 years ago

7 0

Answer:

33.33 %

Explanation:

given,

error last year = 63

error this year = 42

percent decrease in the error = ?

to find the percentage difference in the error formula used is

= $\dfrac{difference}{original}\times 100$

= $\dfrac{63-42}{63}\times 100$

= $\dfrac{21}{63}\times 100$

= 33.33 %

Percentage decrease in the number of error is equal to 33.33%.

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A block with mass m = 0.450 kg is attached to one end of an ideal spring and moves on a horizontal frictionless surface. The oth

svetoff [14.1K]

Answer:

k = 26.25 N/m

Explanation:

given,

mass of the block= 0.450

distance of the block = + 0.240

acceleration = a_x = -14.0 m/s²

velocity = v_x = + 4 m/s

spring force constant (k) = ?

we know,

x = A cos (ωt - ∅).....(1)

v = - ω A cos (ωt - ∅)....(2)

a = ω²A cos (ωt - ∅).........(3)

$\omega = \sqrt{\dfrac{k}{m}}$

now from equation (3)

$a_x = \dfrac{k}{m}x$

$k = \dfrac{m a_x}{x}$

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k = 26.25 N/m

hence, spring force constant is equal to k = 26.25 N/m

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2 years ago

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Stacy measures two quantities: the mass of each washer and the force that the washers exert on the force meter. In general, how

geniusboy [140]

Answer:

When she adds more washers to the meter, the magnitude of force that is shown on the force meter increases.

Explanation:

The force that the washers exert on the force meter is actually the weight of the washers. Weight is actually a force with gravitation acceleration.

F = W = mg

Where g is gravitational acceleration and its value is 9.81 m/s² and m is the mass of any object. As she adds more washers to the meter so the total mass of the washers increases. As the mass of the washers increases, magnitude of the force (Weight) shown on the force meter increases.

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1 year ago

The temperature, T, of a gas is jointly proportional to the pressure P of the gas and the volume V occupied by the gas. Use C as

AnnZ [28]

Answer:

T=C*P*V

Explanation:

It is said that a variable - let's call 'y' -, is proportional to another - let's call it 'x' - if x and y are multiplicatively connected to a constant 'C'. It means that their product (x*y) can be always equaled to the constant 'C' or their division ( $\frac{x}{y}$ ) can be always equaled to 'C'. The first case is the case of the inverse proportionality: It is said that x and y are inversely proportional if

$x*y=C$

The second case is the case of the direct proportionality: It is said that x and y are directly proportional if

$\frac{x}{y} =C$ : x is directly proportional to y.

or

$\frac{y}{x} =C$ : y is directly proportional to x.

Always that any text does not specify about directly or inversely proportionality, it is assumed to mean directly automatically.

For our case, we are said that the temperature T is proportional to the pressure P and the volume V (we assume that it means directly); it is a double proportionality but follows the same rules:

If T were just proportional to P, we would have:

$\frac{T}{P} =C$

If T were just proportional to V, we would have:

$\frac{T}{V} =C$

As T is proportional to both P and V, the right equation is:

$\frac{T}{P*V}=C$

In order to isolate the temperature, let's multiply (P*V) at each side of the equation:

$\frac{T}{P*V}*(P*V)=C*(P*V)\\T=C*P*V$

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1 year ago

An engineer is designing a process for a new transistor. She uses a vacuum chamber to bombard a thin layer of silicon with ions

adelina 88 [10]

Answer:

$E=5.7\times 10^{-3}\ V/m$

Explanation:

Given that

$m_p=5.18\times 10^{-26}\ kg$

re= 46 cm

Vp= 180 m/s

We know that

$E=\dfrac{\Delta V}{r}$

$\Delta V=\dfrac{1}{4}\dfrac{m_pv_p^2}{e}$

So

$E=\dfrac{1}{4}\dfrac{m_pv_p^2}{e.r_e}$

Now by putting the all given values in the questions

$E=\dfrac{1}{4}\times \dfrac{5.18\times 10^{-26}\times 180^2}{1.6\times 10^{-19}\times 0.46}$

$E=5.7\times 10^{-3}\ V/m$

So the average electric field is $E=5.7\times 10^{-3}\ V/m$ .

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1 year ago

In a house the temperature at the surface of a window is 28.9 °C. The temperature outside at the window surface is 7.89 °C. Heat

Alenkasestr [34]

Answer:

-13.18°C

Explanation:

To develop the problem it is necessary to consider the concepts related to the thermal conduction rate.

Its definition is given by the function

$\frac{Q}{t} = \frac{kA\Delta T}{d}$

Where,

Q = The amount of heat transferred

t = time

k = Thermal conductivity constant

A = Cross-sectional area

$\Delta T =$ The difference in temperature between one side of the material and the other

d= thickness of the material

The problem says that there is a loss of heat twice that of the initial state, that is

$Q_2 = 2*Q_1$

Replacing,

$kA\frac{\Delta T_m}{x} = 2*kA\frac{\Delta T}{x}$

$\frac{\Delta T}{x}=2*\frac{\Delta T}{x}$

$\frac{T_i-T_o}{x} = 2\frac{T_1-T_2}{x}$

$\frac{28.9-T_o}{x} = 2\frac{28.9-7.86}{x}$

Solvinf for $T_o$ ,

$T_o = -13.18$

Therefore the temprature at the outside windows furface when the heat lost per second doubles is -13.18°C

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1 year ago