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2 years ago

A 13.3 kg box sliding across the ground

Physics

1 answer:

adelina 88 [10]2 years ago

5 0

Answer:

0.25

Explanation:

According to newtons law of motion

\sum F_x = ma

F_f = ma

nR = ma

nmg = ma

ng = a

n = a/g

g is the acceleration due to gravity

Given

a = 2.42m/s²

g = 9.8m/s²

Substitute into the formula;

n = 2.42/9.8

n = 0.25

Hence the coefficient of kinetic friction is 0.25

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Why must objects be cooled before their mass is determined on a sensitive balance?

zubka84 [21]

Objects should be cooled before their mass is determined on a sensitive balance because it could damage the balance. Also, because it would give you wrong reading of the mass. Hot objects would warm the air around it. A warm air would expand and would produce convection as it rises causing to give the object a mass that is less than the actual. Another reason would be it would cause instability in the readings, the mass would fluctuate every now and then due to the convection currents around the object. It is always recommended to weigh the masses of objects that are in room temperature.

5 0

3 years ago

Find the wavelength of the third line in the lyman series, and identify the type of em radiation.

Natalija [7]

The wavelength of the third line in the Lyman series, and identify the type of EM radiation

In this series, the spectral lines are obtained when an electron makes a transition from any high energy level (n=2,3,4,5... ). The wavelength of light emitted in this series lies in the ultraviolet region of the electromagnetic spectrum.

1 / lambda = R(h)* ( $\frac{1}{(n1)^{2} }$ - $\frac{1}{(n2)^{2} }$ )

= 109678 ( $\frac{1}{1^{2} }$ - $\frac{1}{3^{2} }$ )

= 109678 (8/9)

Lambda = 9 / (109678 * 8 )

= 102.6 * $10^{-9}$ m = 102.6 nm

To learn more about Lyman series here

brainly.com/question/5762197

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8 0

1 year ago

A sinusoidal voltage is given by the expression ????(????)=20cos(5π×103 ????+60°) V. Determine its (a) frequency in hertz, (b) p

MA_775_DIABLO [31]

There are some placeholders in the expression, but they can be safely assumed

Answer:

(a) $f=1617.9\ Hz$

(b) $T=0.618\ ms$

(d) $\varphi=60^o$

Explanation:

Sinusoidal Waves

An oscillating wave can be expressed as a sinusoidal function as follows

$V(t)&=A\cdot \sin(2\pi ft+\varphi )$

Where

$A=Amplitude$

$f=frequency$

$\varphi=Phase\ angle$

The voltage of the question is the sinusoid expression

$V(t)=20cos(5\pi\times 103t+60^o)$

(a) By comparing with the general formula we have

$f=5\pi\times 103=1617.9\ Hz$

$\boxed{f=1617.9\ Hz}$

(b) The period is the reciprocal of the frequency:

$\displaystyle T=\frac{1}{f}$

$\displaystyle T=\frac{1}{1617.9\ Hz}=0.000618\ sec$

Converting to milliseconds

$\boxed{T=0.618\ ms}$

$\boxed{A=20 \ Volts}$

(d) Phase angle:

$\boxed{\varphi=60^o}$

4 0

2 years ago

A 850-kg sports car accelerates from rest to 95 km/h in 6.8 s .

swat32

From the calculations, the power expended is 43650 W.

<h3>What is the power expended?</h3>

Now we can find the acceleration from;

v = u + at

u = 0 m/s

v = 95 km/h or 26.4 m/s

t = 6.8 s

a = ?

Now

v = at

a = v/t

a = 26.4 m/s/ 6.8 s

a = 3.88 m/s^2

Force = ma = 850-kg * 3.88 m/s^2 = 3298 N

The distance covered is obtained from;

v^2 = u^2 + 2as

v^2 = 2as

s = v^2/2a

s = (26.4)^2/2 * 3.88

s = 696.96/7.76

s = 90 m

Now;

Work = Fs

Work = 3298 N * 90 m = 296820 J

Power = 296820 J/ 6.8 s

= 43650 W

Learn more about power expended:brainly.com/question/11579192

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5 0

2 years ago

. Each valve A, B, and C, when open, releases water into a tank at its own constant rate. With all three valves open, the tank f

olasank [31]

Answer:

Time taken by A and B is 1.2 hr.

Explanation:

Given that

Time taken by tank when all(A+B+C) are open = 1 hr

Time taken by tank when A+C are open = 1.5 hr

Time taken by tank when B+C are open = 2 hr

If we treat as filling of tank is a work then

Work = time x rate

Lets take work is 1 unit

1 = 1(1/a+1/b+1/c) ---------1

1 = 1.5(1/a+1/c) ----------2

1 = 2(1/b+1/c) --------3

From equation 1 and 3

1=1(1/a+1/2)

a=2

Form equation 2

1 = 1.5(1/2+1/c)

c=6

From equation 3

1 = 2(1/b+1/6)

b=3

So time taken by

A is alone to fill tank is 2 hr

B is alone to fill tank is 3 hr

C is alone to fill tank is 6 hr

So $time\ taken\ by\ A\ and\ B =\dfrac{2\times 3}{2+3} hr$

Time taken by A and B is 1.2 hr.

7 0

3 years ago