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Sveta_85 [38]
3 years ago
13

At an accident scene on a level road, investigators measure a car's skid mark to be 93 m long. It was a rainy day and the coeffi

cient of friction was estimated to be 0.35. Use these data to determine the speed of the car when the driver slammed on (and locked) the brakes. Express your answer to two significant figures and include the appropriate units
Physics
1 answer:
USPshnik [31]3 years ago
6 0

Answer:

u = 25 m/s

Explanation:

given,                                

length of skid = 93 m          

coefficient of friction = 0.35

final velocity = 0 m/s              

initial velocity = ?                        

force here is friction  f = μ mg

F = ma                                                

now com paring                      

-μ mg = m a                      

a = - μ g                    

a = - 0.35 x 9.8              

a = -3.43 m/s²

we know,              

v² = u² + 2 a s                        

0 = u² - 2 x 3.43 x 93                

u² = 637.98                    

u = 25.26 m/s                      

u = 25 m/s (two significant figure)

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The component of the external magnetic field along the central axis of a 78-turn circular coil of radius 34.0 cm decreases from
grigory [225]

Answer:

Induced current, I = 18.88 A

Explanation:

It is given that,

Number of turns, N = 78

Radius of the circular coil, r = 34 cm = 0.34 m

Magnetic field changes from 2.4 T to 0.4 T in 2 s.

Resistance of the coil, R = 1.5 ohms

We need to find the magnitude of the induced current in the coil. The induced emf is given by :

\epsilon=-N\dfrac{d\phi}{dt}

Where

\dfrac{d\phi}{dt} is the rate of change of magnetic flux,

And \phi=BA

\epsilon=-NA\dfrac{dB}{dt}

\epsilon=-78\times \pi (0.34)^2\dfrac{(0.4-2.4)}{2}

\epsilon=28.32\ V

Using Ohm's law, \epsilon=I\times R

Induced current, I=\dfrac{\epsilon}{R}

I=\dfrac{28.32}{1.5}

I = 18.88 A

So, the magnitude of the induced current in the coil is 18.88 A. Hence, this is the required solution.

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2 years ago
What safety measures would you suggest to protect from harmful waves​
AfilCa [17]

Answer:

If you're talking about the sun than:

Time, Distance and Shielding Time, distance, and shielding actions minimize your exposure to radiation in much the same way as they would to protect you against overexposure to the sun:

If you're talking about the ocean than:

Water safety precautions for teens and young adults:

Never go into the water if you can’t swim.

If you can’t swim, learn. Any age can receive swimming lessons.

Always wear a life jacket while boating or taking part in boating activities such as tubing or skiing.

Never swim alone or in an unsupervised area.

Know your swimming strength.

Don’t rough house around water. Never push, jump on or hang on to others in or around water.

Never drink alcohol while taking part in water or boating activities. Alcohol affects your motor skills therefore making it harder to swim, float, keep balance or drive.

Explanation:

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3 years ago
4. Two straight wires are parallel and carry currents of 1.2 A in opposite directions, as shown. Find the direction of the magne
ANEK [815]
The directions of magnetic force and magnetic field lines are shown in the figure.

The direction to find out the magnetic field lines is given by right hand curl rule. If the thumb shows the direction of current, then the curling fingers show the direction of magnetic field lines.

The direction of force can be given by right hand thumb rule, where

Thumb - Direction of magnetic field lines
Forefinger - Magnetic force
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Such that forefinger, centre finger and thumb must be at 90 degrees to each other.


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3 years ago
In preparation for building a space station, an astronaut removes a self-telescoping uniform rod from the cargo bay and releases
emmainna [20.7K]

To solve this problem it is necessary to apply the concepts related to the conservation of angular momentum. This can be expressed mathematically as a function of inertia and angular velocity, that is:

L = I\omega

Where,

I = Moment of Inertia

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For the given object the moment of inertia is equivalent to

I = \frac{mr^2}{12}

Considering that the moment of inertia varies according to distance, and that there are two of these without altering the mass we will finally have to

L_i = L_f

I_i \omega_1 = I_f \omega_2

(\frac{mr_{initial}^2}{12})(\omega_1)=(\frac{mr_{final}^2}{12})(\omega_2)

(r_{initial}^2})(\omega_1)=(r_{final}^2)(\omega_2)

Our values are given as,

r_{initial} = 3m\\\omega_1 = 0.05rad/s \\r_{final}=1.5m

Replacing we have,

(3^2})(0.05)=(1.5^2)(\omega_2)

\omega_2 = 0.2rad/s

Therefore the angular speed after the catch slips is 0.2rad/s

7 0
2 years ago
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alina1380 [7]

Answer:

1.40625 kg-m^2

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Supposing we have to calculate rotational moment of inertia

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The constant angular velocity of the system, ω= 5010 rev/min

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I_{sys}= mL^2= 2.50\times 0.75^2

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