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Anna35 [415]
3 years ago
9

You drop a ball from a height of 1.7 m, and it bounces back to a height of 1.2 m.

Physics
1 answer:
leva [86]3 years ago
8 0

Answer:

A)       ΔEm = 0.29,  B)   v₁ = 5.8 m/s, c)   v₂=  4.9 m / s    D) the correct answer from 4

Explanation:

For this exercise we will use conservation of energy, taking care of how to choose our system

A) For this case we take two instants

starting point. When the ball goes out

        Em₀ = U = m g y₁

Final point. When the ball reaches its maximum height

         Em_{f} = U = m g y₂

In this case we see that there is a loss of mechanical energy at the moment of rebound, therefore the fraction of energy lost is

          ΔEm = Em_{f} / Em₀

          ΔEm = mg y₂ / mg y₁

          ΔEm = y₂ / y₁

          ΔEm = 1.2 / 1.7

the lost part of energy  

          ΔEm = 1 -0.706

          ΔEm = 0.29

B) the velocity just before the bounce

starting point. When the ball is released

          Em₀ = U = m g y₁

final punot. Just wide of the bounce

           Em_{f} = K = ½ m v₁²

As it has not yet rebounded, it has no energy loss, therefore the mechanical energy is conserved

            Em₀ = Em_{f}

            m g y₁ = ½ m v₁²

             v₁ = √ 2 g y₁

let's calculate

            v₁ =√ (2 9.8 1.7)

             v₁ = 5.77 m / s

            v₁ = 5.8 m/s

C) the velocity just after the bounce

   starting point, after bounce

               Em₀ = K = ½ m v₂²

   final point. Maximum height after bounce

               Em_{f} = U = m g y₂

as it already bounced, the energy is conserved in this interval

               Em₀ = Em_{f}

               ½ m v₂² = m g y₂

               v₂ = √ (2 g y₂)

               v₂ = √ (2 9.8 1.2)

               v₂ = 4.85 m / s

               v₂=  4.9 m / s

D) during the time that the bounce lasts, there is a strong change in energy, part of it is transformed into thermal energy, due to several processes: friction, change in the potential energy of the molecules of the ball, change in the internal energy of the balls. molecules.

Therefore we cannot specify a single process, consequently the correct answer from 4

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spin [16.1K]

Downwards - from uphill towards the lowlands and eventually into the sea.

8 0
3 years ago
Un proyectil es lanzado horizontalmente desde una altura de 12 metro con una velocidad de 80 m/sg. a.Calcular el tiempo de vuelo
Naily [24]

Answer:

t= 1,56 s ,   x= 124,8 m , v = (80 i^ - 15,288 j ) m/s

Explanation:

Este es un ejercicio de lanzamiento proyectiles, comencemos por encontrar el tiempo que tarda en llegar al piso

        y = y₀ + v_{oy} t – ½ g t²

en este caso la altura inicial es y₀= 12 m y llega a y=0 , como es lanzado horizontalmente la velocidad vertical es cero (v_{oy}=0)

       0 = y₀ – ½ g t²

       t= √ (2 y₀/g)

calculemos

       t= √ ( 2 12 / 9,8)

       t= 1,56 s

El alcance del proyectil es la distancia horizontal recorrida  

        x = v₀ₓ t

        x = 80 1,56

        x= 124,8 m

La velocidad de impacto cuando toca el suelo

        vx = v₀ₓ = 80 ms

        v_{y} = v_{oy} – gt

        v_{y} = - 9,8 1,56

        v_{y} = - 15,288 m/s

la velocidad es

       v = (80 i^ - 15,288 j ) m/s

Traducttion  

This is a projectile launching exercise, let's start by finding the time it takes to reach the ground

        y = y₀ + v_{oy} t - ½ g t²

in this case the initial height is i = 12 m and it reaches y = 0, as it is thrown horizontally the vertical speed is zero (v_{oy} = 0)

       0 =y₀I - ½ g t²

       t = √ (2y₀ / g)

let's calculate

       t = √ (2 12 / 9.8)

       t = 1.56 s

Projectile range is the horizontal distance traveled

        x = v₀ₓ t

        x = 80 1.56

        x = 124.8 m

Impact speed when it hits the ground

        vₓ = v₀ₓ = 80 ms

        v_{y} = v_{oy} - gt

        v_{y} = - 9.8 1.56

        v_{y} = - 15,288 m / s

the speed is

       v = (80 i ^ - 15,288 j) m / s

7 0
3 years ago
An obiect of mass weighing 5,24 k acceleration due to gravity is 9 8 meters/second2 is raised to a height of 1.63 meters. What i
Julli [10]
83.79 J (using significant digits)
7 0
3 years ago
Water from a fire hose is directed horizontally against at a rate of 50.0 kg/s and a speed of 42.0 m/s.
ss7ja [257]

Answer:

Force, |F| = 2100 N

Explanation:

It is given that,

Water from a fire hose is directed horizontally against at a rate of 50.0 kg/s, \dfrac{m}{t}=50\ kg/s

Initial speed, v = 42 m/s

The momentum is reduced to zero, final speed, v = 0

The relation between the force and the momentum is given by :

F=\dfrac{p}{t}

F=\dfrac{mv}{t}

F=50\ kg/s\times 42\ m/s

|F| = 2100 N

So, the magnitude of the force exerted on the wall is 2100 N. Hence, this is the required solution.

8 0
3 years ago
The y component of the electric field of an electromagnetic wave traveling in the +x direction through vacuum obeys the equation
Alexxx [7]

Answer: 8.6 µm

Explanation:

At a long distance from the source, the components (the electric and magnetic fields) of the electromagnetic waves, behave like plane waves, so the equation for the y component of the electric field obeys an equation like this one:

Ey =Emax cos (kx-ωt)

So, we can write the following equality:

ω= 2.2 1014 rad/sec

The angular frequency and the linear frequency are related as follows:

f = ω/ 2π= 2.2 1014 / 2π (rad/sec) / rad = 0.35 1014 1/sec

In an electromagnetic wave propagating through vacuum, the speed of the wave is just the speed of light, c.

The wavelength, speed and frequency, are related by this equation:

λ = c/f

λ = 3.108 m/s / 0.35. 1014 1/s = 8.6 µm.

7 0
3 years ago
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