Which statement about friction in a system is true?(1 point)

Triss [41]

A non-moving bike has wheels that aren't spinning and zero angular momentum, which makes it very easy for external torque to change the wheels' direction, making the bike harder to balance. Even when staying relatively motionless, though, a rider can balance a bike with some effort.

5 0

3 years ago

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A capacitor with an initial potential difference of 100 V isdischarged through a resistor when a switch between them is closed a

jonny [76]

Answer:

(a). The time constant of the circuit is 2.17.

(b). The potential difference across the capacitor at t=17.0 s is 0.0396 V.

Explanation:

Given that,

Initial potential difference = 100 V

Potential difference across the capacitor = 1.00 V

(a). We need to calculate the time constant of the circuit

Using formula of potential difference

$V(t)=V_{0}e^{\dfrac{-t}{RC}}$

Put the value into the formula

$1.00=100e^{\dfrac{-10.0}{RC}}$

$0.01=e^{\dfrac{-10.0}{RC}}$

On taking ln

$ln(0.01)=\dfrac{-10}{RC}$

$RC=\dfrac{-10}{ln(0.01)}$

$RC=2.17$

(b). We need to calculate the potential difference across the capacitor at t=17.0 s

Using formula again

$V(17)=100e^{\dfrac{-17}{2.17}}$

$V{17}=0.0396\ V$

Hence, (a). The time constant of the circuit is 2.17.

(b). The potential difference across the capacitor at t=17.0 s is 0.0396 V.

7 0

3 years ago

Technician A says that power is the rate that energy is stored. Technician B says that power refers to the rate that energy is t

Alex777 [14]

Answer:

C. Both technicians A and B

Explanation:

From the physical definition, power is defined as the rate of a body doing work. It is expressed as

P = w/t watts

Where

w - is the work done or the energy of the system in joules

t - time

The unit of power is represented in watts.

Whenever there is a rate of change of energy in the system, it accounts for the efficiency of the power of the system.

Hence, the statements of both technicians are correct.

7 0

3 years ago

A disk with a radius of R is oriented with its normal unit vector at an angle Θ with respect to a uniform electric field. Which

marissa [1.9K]

Answer:

The expresion for the flux through the disk is:

Ф = E·πR^2·cos(Θ).

Explanation:

Let's sat the electric field has direction e and the normal to the disk has direction n (bold means vector quantities). So we have:

E=E·e (where E is the magnitud of the electric flied)

A=A·n

The flux for an uniform electric field and a flat surface is:

Ф=E×A

⇒ Ф = E·A·e×n = E·A·cos(angle(e,n)) = E·A·cos(Θ)

Since in this case the area is for a disk of radius R, $A=\pi R^{2}$

So, Ф = E·πR^2·cos(Θ)

8 0

3 years ago

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A spaceship whose rest length is 350m has a speed of .82c

igomit [66]

Answer:

$t'=1.1897*10^{-6} s$

t'=1.1897 μs

Explanation:

First we will calculate the velocity of micrometeorite relative to spaceship.

Formula:

$u=\frac{u'+v}{1+\frac{u'*v}{c^{2}}}$

where:

v is the velocity of spaceship relative to certain frame of reference = -0.82c (Negative sign is due to antiparallel track).

u is the velocity of micrometeorite relative to same frame of reference as spaceship = .82c (Negative sign is due to antiparallel track)

u' is the relative velocity of micrometeorite with respect to spaceship.

In order to find u' , we can rewrite the above expression as:

$u'=\frac{v-u}{\frac{u*v}{c^{2} }-1 }$

$u'=\frac{-0.82c-0.82c}{\frac{0.82c*(-0.82c)}{c^{2} }-1 }$

u'=0.9806c

Time for micrometeorite to pass spaceship can be calculated as:

$t'=\frac{length}{Relatie seed (u')}$

$t'=\frac{350}{0.9806c}$ (c = 3*10^8 m/s)

$t'=\frac{350}{0.9806* 3.0*10^{8} }$

$t'=1.1897*10^{-6} s$

t'=1.1897 μs

4 0

3 years ago