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3 years ago

A girl running around a circular track of radius 200 m completes one

Physics

1 answer:

kondor19780726 [428]3 years ago

4 0

Answer:

v = 2 m/s

Explanation:

First, we find the angular velocity of the girl by using the following formula:

$Angular\ Velocity =\omega= \frac{Angular\ Distance\ Covered}{Time\ Taken}\\\\\omega = \frac{1\ revolution}{10\ min}\frac{1\ min}{60\ s}\frac{2\pi\ rad}{1\ revolution}\\\\\omega = 0.01\ rad/s$

Now, for the average velocity of the girl we can use the following formula:

$Average\ Velocity = V = r\omega\\V = (200\ m)(0.01\ rad/s)\\$

where,

r = radius = 200 m

therefore,

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A pair of electrically charged objects attract each other with a force of 4 N when they are a distance of 3 m apart. If their ch

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Answer:

1 N

Explanation:

From coulomb's law,

The force of attraction between two charges is inversely proportional to the square of the distance between the charges.

From the question,

Assuming the charges are the same in both case,

F ∝ /r²....................... Equation 1

Fr² = k

F'r'² = Fr²........................... Equation 2

Where F' = First Force, r'² = First distance, F = second force, r² = second distance.

make F the subject of the equation,

F = F'r'²/r².................... Equation 3

Given: F' = 4 N, r' = 3 m, r = 6 m

Substitute into equation 3

F = 4(3²)/6²

F = 36/36

F = 1 N

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3 years ago

The “turning effect of a force” (T = F * r) is:

Doss [256]

Answer:

b and e

Explanation:

r x F is the formula for torque.

The "turning effect" or torque happens when concentric forces rotate an object along said center.

a) False because T = Fr = Ia (a = angular acceleration)

b) True

c) False. L = Iw (w = angular velocity), which does not equal Ia

d) False. It is torque, not the product of torque and something else

e) True.

8 0

3 years ago

A coil has N turns enclosing an area of A. In a physics laboratory experiment, the coil is rotated during the time interval Δt f

scoray [572]

Answer:

$\dfrac{NBA}{\Delta t}$

Explanation:

B = Magnetic field

A = Area

$\theta$ = Angle

t = Time taken

Before rotation the magnetic flux is given by

$\phi_i=BAsin\theta\\\Rightarrow \phi_i=BAsin90\\\Rightarrow \phi_i=BA$

Magnetic flux is BA

After rotation the magnetic flux is given by

$\phi_i=BAsin\theta\\\Rightarrow \phi_i=BAsin0\\\Rightarrow \phi_i=0$

The magnetic flux is 0

Magnitude of emf is given by

$\epsilon=NA\dfrac{d\phi}{dt}\\\Rightarrow \epsilon=\dfrac{NBA}{\Delta t}$

The magnitude of the average emf induced in the entire coil is $\dfrac{NBA}{\Delta t}$

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3 years ago

A proton is a subatomic particle that carries a ___________ charge

Dovator [93]

The answer would be a positive charge

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3 years ago

An engine draws energy from a hot reservoir with a temperature of 1250 K and exhausts energy into a cold reservoir with a temper

dimulka [17.4K]

Answer:

The power output of this engine is $P = 17.5 W$

The the maximum (Carnot) efficiency is $\eta_c = 0.7424$

The actual efficiency of this engine is $\eta _a = 0.46$

Explanation:

From the question we are told that

The temperature of the hot reservoir is $T_h = 1250 \ K$

The temperature of the cold reservoir is $T_c = 322 \ K$

The energy absorbed from the hot reservoir is $E_h = 1.37 *10^{5} \ J$

The energy exhausts into cold reservoir is $E_c = 7.4 *10^{4} J$

The power output is mathematically represented as

$P = \frac{W}{t}$

Where t is the time taken which we will assume to be 1 hour = 3600 s

W is the workdone which is mathematically represented as

$W = E_h -E_c$

substituting values

$W = 63000 J$

$P = \frac{63000}{3600}$

$P = 17.5 W$

The Carnot efficiency is mathematically represented as

$\eta_c = 1 - \frac{T_c}{T_h}$

$\eta_c = 1 - \frac{322}{1250}$

$\eta_c = 0.7424$

The actual efficiency is mathematically represented as

$\eta _a = \frac{W}{E_h}$

substituting values

$\eta _a = \frac{63000}{1.37*10^{5}}$

$\eta _a = 0.46$

7 0

3 years ago