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Marizza181 [45]
3 years ago
6

John is traveling north at 20 meters/second and his friend Betty is traveling south at 20 meters/second. If north is the positiv

e direction, what are John and Betty's speeds? -20 meters/second, 20 meters/second 20 meters/second, 20 meters/second -20 meters/second, -20 meters/second 0 meters/second, 40 meters/second Done
Physics
2 answers:
Alexxx [7]3 years ago
4 0

Answer:

20 meters/second -20 meters/second

Explanation:

John is travelling north at 20 meters/second. If north is the positive direction, then John is travelling at +20 meters/second, or just 20 m/s.

Betty is travelling south at 20 meters/second, then she is travelling in the negative direction, making her speed -20 meters/second.

Tpy6a [65]3 years ago
3 0
I think it's just 20/20
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a wave is described by where x is in meters, y is in centimeters and t is in seconds. The angular frequency is
Sergeeva-Olga [200]

Complete Question

A wave is described by y(x,t) = 0.1 sin(3x + 10t), where x is in meters, y is in centimetres and t is in seconds. The angular wave  frequency is

Answer:

The  value is w =  10 \ rad /s

Explanation:

From the question we are told that  

    The equation describing the wave is y(x,t) = 0.1 sin(3x + 10t)

Generally the sinusoidal equation representing the motion of a wave is mathematically represented as

         y(x,t) =  Asin(kx + wt )

Where  w  is the  angular frequency

Now comparing this equation  with that given we see that

       w =  10 \ rad /s

 

               

7 0
3 years ago
Starting from rest, a basketball rolls from the top to the bottom of a hill, reaching a translational speed of 6.1 m/s. Ignore f
tatiyna

Answer:

a) h=3.16 m, b)  v_{cm }^ = 6.43 m / s

Explanation:

a) For this exercise we can use the conservation of mechanical energy

Starting point. Highest on the hill

           Em₀ = U = mg h

final point. Lowest point

           Em_{f} = K

Scientific energy has two parts, one of translation of center of mass (center of the sphere) and one of stationery, the sphere

           K = ½ m v_{cm }^{2} + ½ I_{cm} w²

angular and linear speed are related

           v = w r

           w = v / r

            K = ½ m v_{cm }^{2} + ½ I_{cm} v_{cm }^{2} / r²

            Em_{f} = ½ v_{cm }^{2} (m + I_{cm} / r2)

as there are no friction losses, mechanical energy is conserved

             Em₀ = Em_{f}

             mg h = ½ v_{cm }^{2} (m + I_{cm} / r²)         (1)

             h = ½ v_{cm }^{2} / g (1 + I_{cm} / mr²)

for the moment of inertia of a basketball we can approximate it to a spherical shell

             I_{cm} = ⅔ m r²

we substitute

            h = ½ v_{cm }^{2} / g (1 + ⅔ mr² / mr²)

            h = ½ v_{cm }^{2}/g    5/3

             h = 5/6 v_{cm }^{2} / g

           

let's calculate

           h = 5/6 6.1 2 / 9.8

           h = 3.16 m

b) this part of the exercise we solve the speed of equation 1

          v_{cm }^{2} = 2m gh / (1 + I_{cm} / r²)

in this case the object is a frozen juice container, which we can simulate a solid cylinder with moment of inertia

              I_{cm} = ½ m r²

we substitute

             v_{cm } = √ [2gh / (1 + ½)]

             v_{cm } = √(4/3 gh)

let's calculate

             v_{cm } = √ (4/3 9.8 3.16)

             v_{cm }^ = 6.43 m / s

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The solution is in the attachment

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Answer:

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3 years ago
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