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Levart [38]
3 years ago
8

Which of the following statements about electric field lines are true? (choose all that are true) a) They are only defined for p

ositive charges.
b) They are always tangent to electric field vectors.
c) They are always perpendicular to charged surfaces.
d) They are a simple way to visualize the electric field vectors. e) None of the above.
Physics
1 answer:
cupoosta [38]3 years ago
8 0

Answer:  b) TRUE and d) TRUE

Explanation:  a) FALSE the electric field lines are used to represent the charges postives and negatives.

b) TRUE it is the definition of  electric field lines , they are tangent to the electric field vector.

c) FALSE  the electric field lines only for conductor are perpendicular to the surface in other any situation there is a tangencial electric field components.

d) TRUE since it is a way to describe and imagine the effect of vectorial fields.

e) FALSE

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A 25,000 kg traveling east collides with a 2,000 kg truck standing still on the tracks. After the collision the train and truck
Elis [28]

Answer:

24.084 m/s

Explanation:

From the law of conservation of linear momentum

Total momentum before collision equals to the total momentum after collision

Since momentum=mv where m is mass and v is velocity

M_{truck}V_{truck}=V_{common}*(M_{truck} +M_{standing}) where M_{truck} is the mass of the truck, V_{truck} is velocity of the truck, V_{common} is the common velocity of moving and standing truck after collision and M_{standing} is the mass of the standing truck

Making V_{truck} the subject we obtain

V_{truck}=\frac { V_{common}*(M_{truck} +M_{standing})}{M_{truck}}

Substituting M_{truck} as 25000 Kg, V_{common} as 22.3 m/s, M_{standing} as 2000 Kg we obtain

V_{truck}=\frac { 22.3 m/s *(25000 Kg +2000 Kg)}{25000}= 24.084 m/s

Therefore, assuming no friction and considering that after collision they still move eastwards hence common velocity and initial truck velocities are positive

The truck was moving at 24.084 m/s

3 0
3 years ago
Awave has a period of 1. What is its frequency?
Andrei [34K]

Answer:

Frequency, f = 1 unit

Explanation:

It is given that,

Period of the wave, T = 1 unit

We need to find the frequency of the wave. There exist an inverse relationship between period and the frequency of the wave. It is given by :

T=\dfrac{1}{f}

Or

f=\dfrac{1}{T}

f=\dfrac{1}{1\ units}

f = 1 unit

So, the frequency of the wave is 1 unit. Hence, this is the required solution.

4 0
3 years ago
A contestants spin a wheel when it is their turn in a game show. One contestant gives the wheel an initial angular speed of 3.40
guajiro [1.7K]

Answer:

4.62 s

Explanation:

We are given that

Initial angular speed,\omega=3.4 rad/s

\theta=1\frac{1}{4} rev=\frac{5}{4}\times 2\pi=2.5\pi rad

\omega'=0

\omega'^2-\omega^2=2\alpha \theta

Substitute the values

0-(3.4)^2=2\times 2.5\pi \alpha

\alpha=\frac{-(3.4)^2}{2\times 2.5\pi}=-0.736 rad/s^2

\omega'=\omega+\alpha t

0=3.4-0.736 t

-0.736t=-3.4

t=\frac{-3.4}{-0.736}=4.62 s

Hence, the wheel takes 4.62 s to come to rest.

3 0
3 years ago
Inez uses hairspray on her hair each morning before going to school. The spray spreads out before reaching her hair partly becau
Tamiku [17]

Answer:

7.0\cdot 10^{-13}C

Explanation:

The magnitude of the electrostatic force between two charged objects is

F=k\frac{q_1 q_2}{r^2}

where

k is the Coulomb's constant

q1 and q2 are the two charges

r is the separation between the two charges

The force is attractive if the charges have opposite sign and repulsive if the charges have same sign.

In this problem, we have:

r=0.070 cm =7\cdot 10^{-4} m is the distance between the charges

q_1=q_2=q since the charges are identical

F=9.0\cdot 10^{-9}N is the force between the charges

Re-arranging the equation and solving for q, we find the charge on each drop:

F=\frac{kq^2}{r^2}\\q=\sqrt{\frac{Fr^2}{k}}=\sqrt{\frac{(9.0\cdot 10^{-9})(7\cdot 10^{-4})^2}{8.99\cdot 10^9}}=7.0\cdot 10^{-13}C

8 0
3 years ago
Now imagine a person dragging a 50 kg box along the ground with a rope, as
ANTONII [103]

Answer:

The coefficient of static friction between the box and floor is, μ = 0.061

Explanation:

Given data,

The mass of the box, m = 50 kg

The force exerted by the person, F = 50 N

The time period of motion, t = 10 s

The frictional force acting on the box, f = 30 N

The normal force on the box, η = mg

                                                     = 50 x 9.8

                                                     = 490 N

The coefficient of friction,

                            μ = f/ η

                               = 30 / 490

                               = 0.061

Hence, the coefficient of static friction between the box and floor is, μ = 0.061

7 0
3 years ago
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