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1 year ago

The SI system uses three base units. Is this true or false?

Physics

2 answers:

ozzi1 year ago

8 0

$The\text{ SI }system\text{ uses seven }base\text{ units, hence the statement is false}$

Irina-Kira [14]1 year ago

7 0

The answer is false

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A block of wood is floating in water; it is depressed slightly and then released to oscillate up and down. Assume that the top a

Marysya12 [62]

Explanation:

Equilibrium position in y direction:

W = Fb (Weight of the block is equal to buoyant force)

m*g = V*p*g

V under water = A*h

hence,

m = A*h*p

Using Newton 2nd Law

$-m*\frac{d^2y}{dt^2} = Fb - W\\\\-m*\frac{d^2y}{dt^2} = p*g*(h+y)*A - A*h*p*g\\\\-A*h*p*\frac{d^2y}{dt^2} = y *p*A*g\\\\\frac{d^2y}{dt^2} + \frac{g}{h} * y =0$

Hence, T time period

T = 2*pi*sqrt ( h / g )

4 0

4 years ago

Car A (mass 1100 kg) is stopped at a traffic light when it is rearended by car B(mass 1400 kg). Both cars then slide with locke

viva [34]

Answer:

Part a)

$v_a = 3.94 m/s$

Part b)

$v_b = 3.35 m/s$

Part C)

$v_b = 6.44 m/s$

Part d)

Due to large magnitude of friction between road and the car the momentum conservation may not be valid here as momentum conservation is valid only when external force on the system is zero.

Explanation:

Part a)

As we know that car A moves by distance 6.1 m after collision under the frictional force

so the deceleration due to friction is given as

$a = -\frac{F_f}{m}$

$a = -\frac{\mu mg}{m}$

$a = - \mu g$

now we will have

$v_f^2 - v_i^2 = 2ad$

$0 - v_i^2 = 2(-\mu g)(6.1)$

$v_a = \sqrt{(2(0.13)(9.81)(6.1)}$

$v_a = 3.94 m/s$

Part b)

Similarly for car B the distance of stop is given as 4.4 m

so we will have

$v_b = \sqrt{2(0.13)(9.81)(4.4)}$

$v_b = 3.35 m/s$

Part C)

By momentum conservation we will have

$m_1v_{1i} = m_1v_{1f} + m_2v_{2f}$

$1400 v_b = 1100(3.94) + 1400(3.35)$

$v_b = 6.44 m/s$

Part d)

Due to large magnitude of friction between road and the car the momentum conservation may not be valid here as momentum conservation is valid only when external force on the system is zero.

3 0

3 years ago

A green light is submerged 2.70 m beneath the surface of a liquid with an index of refraction 1.31. What is the radius of the ci

Anettt [7]

Answer:

The radius is $r = 3.1905 \ m$

Explanation:

From the question we are told that

The distance beneath the liquid is $d = 2.70 \ m$

The refractive index of the liquid is $n_i = 1.31$

Now the critical value is mathematically represented as

$\theta = sin ^{-1} [\frac{1}{n_i} ]$

substituting values

$\theta = sin ^{-1} [\frac{1}{131} ]$

$\theta = 49.76^o$

Using SOHCAHTOA rule we have that

$tan \theta = \frac{ r}{d}$

=> $r = d * tan \theta$

substituting values

$r = 2.7 * tan (49.76)$

$r = 3.1905 \ m$

5 0

3 years ago

Why polarization does not occur in dry cell?

Arisa [49]

Answer:

Manganese oxide prevents polarisation in dry cells. - Polarization is a defect that occurs in simple electric cells due to the accumulation of hydrogen gas around the positive electrode. ... - MnO2 reacts with H2 and forms water as byproduct, so depolarization doesn't occur.

7 0

3 years ago

A wire of radius R has a current I uniformly distributed across its cross-sectional area. Ampere's law is used with a concentric

MrMuchimi

Answer:

Please refer to the figure.

Explanation:

The crucial point here is to calculate the enclosed current. If the current I is flowing through the whole cross-sectional area of the wire, the current density is

$J = \frac{I}{\pi R^2}$

The current density is constant for different parts of the wire. This idea is similar to that of the density of a glass of water is equal to the density of a whole bucket of water.

So,

$J = \frac{I}{\pi R^2} = \frac{I_{enc}}{\pi r^2}\\I_{enc} = \frac{Ir^2}{R^2}$