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Step2247 [10]
3 years ago
7

The distance traveled by a race car is 7 km in 100 seconds. what is the speed?

Physics
2 answers:
Lelu [443]3 years ago
8 0
Speed is distance/time so
Speed = 7000m/100s=70m/s
laila [671]3 years ago
6 0
Speed = Distance/Time
           = 7*1000/100                   (Multiplying by 1000 to convert km in m)
Therefore, 
Speed=70 m/sec

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A stone was dropped off a cliff and hit the ground with a speed of 96 ft/s. What is the height of the cliff? (Use 32 ft/s2 for t
nadezda [96]
The initial velocity of the stone is 0 ft/s. Given the initial velocity (Vi), final velocity (Vf), and acceleration due to gravity (g), the distance may be calculated through the equation,
                                     d = ((Vf)² - (Vi)²) / 2g
Substituting the known values,
                                     d = ((96 ft/s)² - 0))/ (2x32.2)
The value of d is 143.10 ft. 
4 0
3 years ago
The electric field must be zero inside a conductor in electrostatic equilibrium, but not inside an insulator. It turns out that
pav-90 [236]

Answer:

The permittivity of rubber is  \epsilon  = 8.703 *10^{-11}

Explanation:

From the question we are told that

     The  magnitude of the point charge is  q_1 =  70 \ nC  =  70 *10^{-9} \  C

      The diameter of the rubber shell is  d = 32 \ cm  =  0.32 \ m

       The Electric field inside the rubber shell is  E =  2500 \ N/ C

The radius of the rubber is  mathematically evaluated as

              r =  \frac{d}{2} =  \frac{0.32}{2}  =  0.16 \ m

Generally the electric field for a point  is in an insulator(rubber) is mathematically represented as

         E =  \frac{Q}{ \epsilon }  *  \frac{1}{4 *  \pi r^2}

Where \epsilon is the permittivity of rubber

    =>     E  *  \epsilon  *  4 * \pi *  r^2 =  Q

   =>      \epsilon  =  \frac{Q}{E *  4 *  \pi *  r^2}

substituting values

            \epsilon  =  \frac{70 *10^{-9}}{2500 *  4 *  3.142 *  (0.16)^2}

            \epsilon  = 8.703 *10^{-11}

7 0
3 years ago
player kicks a soccer ball from ground level and sends it flying at an angle of 30 degrees at a speed of 26 m/s. What is the hor
seropon [69]

Answer

22.5 m/s

Explanation

We shall use the trigonometric ratio cosine to find the horizontal component.

cos = adjacent/hypotenuse

Adjacent is the horizontal and hypotenuse is the fly speed.

cos 30° = horizontal / 26

horizontal velocity = 26 × cos 30°

                                = 26 × 0.866

                                = 22.5166

                                 = 22.5 m/s

7 0
3 years ago
Read 2 more answers
7.22 Ignoring reflection at the air–water boundary, if the amplitude of a 1 GHz incident wave in air is 20 V/m at the water surf
Serga [27]

Answer:

z = 0.8 (approx)

Explanation:

given,

Amplitude of 1 GHz incident wave in air = 20 V/m

Water has,

μr = 1

at 1 GHz, r = 80 and σ = 1 S/m.

depth of water when amplitude is down to  1 μV/m

Intrinsic impedance of air = 120 π  Ω

Intrinsic impedance of  water = \dfrac{120\pi}{\epsilon_r}

Using equation to solve the problem

  E(z) = E_0 e^{-\alpha\ z}

E(z) is the amplitude under water at z depth

E_o is the amplitude of wave on the surface of water

z is the depth under water

\alpha = \dfrac{\sigma}{2}\sqrt{\dfrac{(120\pi)^2}{\Epsilon_r}}

\alpha = \dfrac{1}{2}\sqrt{\dfrac{(120\pi)^2}{80}}

\alpha =21.07\ Np/m

now ,

  1 \times 10^{-6} = 20 e^{-21.07\times z}

  e^{21.07\times z}= 20\times 10^{6}

taking ln both side

21.07 x z = 16.81

z = 0.797

z = 0.8 (approx)

5 0
3 years ago
Pls help me with this problem!!
Olenka [21]

Answer:

v = 19.6 m/s.

Explanation:

Given that,

The radius of the circle, r = 5 m

The time period of the ball, T = 1.6s

We need to find the ball's tangential velocity.

The formula for the tangential velocity is given by :

v=\dfrac{2\pi r}{T}

Putting all the values in the above formula

v=\dfrac{2\pi \times 5}{1.6}\\\\v=19.6\ m/s

So, the tangential velocity of the ball is 19.6 m/s. Hence, the correct option is (c).

7 0
3 years ago
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