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3 years ago

Materials having resistance changes as voltage or current varies are called:

1 answer:

8 0

I believe they are called nonohmic materials. According to ohms law the current trough a current carrying conductor is directly proportional to the potential difference (voltage) at a constant resistance. Non-ohmic conductors or materials are those materials that do not obey the ohms law, their resistance increases as the current increases. Ohmic materials are those that obeys the ohms law such that the voltage and current are proportional- doubling the potential difference doubles the current.

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An electric wall clock has a second hand 15 cm long. at the tip of his hand, what is the magnitude of the velocity?

Mila [183]

The velocity of the tip of the second hand is 0.0158 m/s

Explanation:

First of all, we need to calculate the angular velocity of the second hand.

We know that the second hand completes one full circle in

T = 60 seconds

Therefore, its angular velocity is:

$\omega = \frac{2\pi}{T}=\frac{2\pi}{(60)}=0.105 rad/s$

Now we can calculate the velocity of a point on the tip of the hand by using the formula

$v=\omega r$

where

$\omega=0.105 rad/s$ is the angular velocity

r = 15 cm = 0.15 m is the radius of the circle (the distance of the point from the centre of rotation)

Substituting,

$v=(0.105)(0.15)=0.0158 m/s$

Learn more about angular motion here:

brainly.com/question/9575487

brainly.com/question/9329700

brainly.com/question/2506028

#LearnwithBrainly

7 0

2 years ago

A 19kg block is being pulled with a constant horizontal force of 95 Newton’s while also experiencing a constant friction force o

yuradex [85]

Answer:

⋅(19kg)=19Akg

95=19Akg

19=19Ak

Explanation:

5 0

3 years ago

Three packing crates of masses, M1 = 6 kg, M2 = 2 kg and M3 = 8 kg are connected by a light string of negligible mass that passe

never [62]

Answer:

39.81 N

Explanation:

I attached an image of the free body diagrams I drew of crate #1 and #2.

Using these diagram, we can set up a system of equations for the sum of forces in the x and y direction.

∑Fₓ = maₓ

∑Fᵧ = maᵧ

Let's start with the free body diagram for crate #2. Let's set the positive direction on top and the negative direction on the bottom. We can see that the forces acting on crate #2 are in the y-direction, so let's use Newton's 2nd Law to write this equation:

∑Fᵧ = maᵧ
T₁ - m₂g = m₂aᵧ

Note that the tension and acceleration are constant throughout the system since the string has a negligible mass. Therefore, we don't really need to write the subscripts under T and a, but I am doing so just so there is no confusion.

Let's solve for T in the equation...

T₁ = m₂aᵧ + m₂g
T₁ = m₂(a + g)

We'll come back to this equation later. Now let's go to the free body diagram for crate #1.

We want to solve for the forces in the x-direction now. Let's set the leftwards direction to be positive and the rightwards direction to be negative.

∑Fₓ = maₓ

F_f - F_g sinΘ = maₓ

The normal force is equal to the x-component of the force of gravity.

(F_n · μ_k) - m₁g sinΘ = m₁aₓ

(F_g cosΘ · μ_k) - m₁g sinΘ = m₁aₓ
[m₁g cos(30) · 0.28] - [m₁g sin(30)] = m₁aₓ
[(6)(9.8)cos(30) · 0.28] - [(6)(9.8)sin(30)] = (6)aₓ
[2.539595871] - [-58.0962595] = 6aₓ
60.63585537 = 6aₓ
aₓ = 10.1059759 m/s²

Now let's go back to this equation:

T₁ = m₂(a + g)

We have 3 known variables and we can solve for the tension force.

T = 2(10.1059759 + 9.8)
T = 2(19.9059759)
T = 39.8119518 N

The tension force is the same throughout the string, therefore, the tension in the string connecting M2 and M3 is 39.81 N.

3 0

2 years ago

The speed of a box traveling on a horizontal friction surface changes from vi = 13 m/s to vf = 11.5 m/s in a distance of d = 8.5

ValentinkaMS [17]

The average power supplied to the box by friction while it slows from 13 m/s to 11.5 m/s is 3.24 W.

<h3>Acceleration of the box</h3>

The acceleration of the box is calculated as follows;

vf² = vi² + 2as

a = (vf² - vi²)/2s

a = (11.5² - 13²) / (2 x 8.5)

a = -2.16 m/s²

<h3>Time of motion of the box</h3>

The time taken for the box to travel is calculated as follows;

a = (vf - vi)/t

t = (vf - vi) / a

t = (11.5 - 13) / (-2.16)

t = 0.69 s

<h3>Average power supplied by the friction</h3>

P = Fv

P = (ma)(vf - vi)

P = (1 x -2.16) x (11.5 - 13)

P = 3.24 W

Thus, the average power supplied to the box by friction while it slows from 13 m/s to 11.5 m/s is 3.24 W.

Learn more about average power here: brainly.com/question/19415290

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7 0

1 year ago

You need to design a 60.0-Hz ac generator that has a maximum emf of 5500 V. The generator is to contain a 150-turn coil that has

olchik [2.2K]

Answer:

So magnetic field will be equal to 0.1144 T

Explanation:

We have given frequency f = 60 Hz

Maximum emf e = 5500 volt

Number of turns N = 150

Area $A=0.85m^2$

Emf generated in ac generator is given $e=NBA\omega sin(\omega t)$

For maximum emf $sin(\omega t)=1$

So maximum emf will be equal to $e=NBA\omega$

$B=\frac{e}{NA\omega }=\frac{5500}{150\times 2\times 3.14\times 60\times 0.85}=0.1144T$

So magnetic field will be equal to 0.1144 T

3 0

3 years ago