A tennis ball of mass 44.0 g is held just above a basketball of mass 594 g. With their centers vertically aligned, both are released from rest at the same moment, to fall through a distance of 1.08 m, (a) Find the magnitude of the downward velocity with which the basketball reaches the ground. Assume that an elastic collision with the ground instantaneously reverses the velocity of the basketball while the tennis ball is still moving down. (b) Next, the two balls meet in an elastic collision. To what height does the tennis ball rebound?

Respuesta :

Answer:

u = 4.6 m/s

h = 8.01 m

Explanation:

Given:

Mass of the tennis ball, m = 44.0 g

Mass of the basket ball, M = 594 g

Height of fall, h = 1.08m

Now,

we have

[tex]u^2-u'^2 = 2as[/tex]

where, s = distance = h

a = acceleration

u = final speed before the collision

u' = initial speed

since it is free fall case

thus,

a = g = acceleration due to gravity

u' = 0

thus we have

[tex]u^2-0^2 = 2\times9.8\tiimes1.08[/tex]

or

[tex]u = \sqrt{21.168}[/tex]

or

u = 4.6 m/s

b) Now after the bounce, the ball moves with the same velocity

thus, v = v₂

thus,

final speed ([tex]v_f[/tex]) = v = 4.6 m/s

Then conservation of energy says  

[tex]\frac{1}{2}mu_1^2+\frac{1}{2}Mu_2^2 = \frac{1}{2}mv_1^2+\frac{1}{2}Mv_2^2[/tex]  

also

applying the concept of conservation of momentum

we have

mu₁ + Mu₂ = mv₁ + Mv₂

u₁ =velocity of the tennis ball before collision = -4.6 m/s  

u₂ = velocity of the basketball before collision= 4.6 m/s  

v₁ =  velocity of the tennis ball after collision  

v₂ = velocity of the basketball  after collision

substituting the values in the equation, we get

Now,

solving both the equations simultaneously we get

[tex]v = (\frac{2M}{m+M})u_1+(\frac{m-M}{m+M})u_2[/tex]

substituting the values in the above equation we get

[tex]v = (\frac{2\times594}{44+594})(-4.6)+(\frac{44-594}{44+594})4.6[/tex]

or

[tex]v = -8.565-3.965[/tex]

or

[tex]v = -12.53m/s[/tex]

here negative sign depicts the motion of the ball in the upward direction

now the kinetic energy of the tennis ball

[tex]K.E = \frac{1}{2}mv^2[/tex]

or

[tex]K.E = \frac{1}{2}44\times 10^{-3}kg\times 12.53^2[/tex]

or

K.E = 3.45 J

also at the height the K.E will be the potential energy of the tennis ball

thus,

3.45 J = mgh

or

3.45 = 44 × 10⁻³ × 9.8 × h

h = 8.01 m

The height to which the tennis ball rebounds is found with the assumption

that it has equal speed with the basketball  before collision.

(a) The magnitude of the downward velocity of the basketball is

approximately 4.6 m/s

(b) The height to which the tennis ball rebounds is approximately 8 meters

Reasons:

Mass of tennis ball, m₁ = 44.0 g

Mass of basketball, m₂ = 594 g

Distance the balls are dropped, h = 1.08 m

(a) The magnitude of the downward velocity, v of the basketball when it

reaches the ground, is given as follows;

v = √(2·g·h)

∴ v = √(2×9.81×1.08) ≈ 4.6

The magnitude of the downward velocity, v ≈ 4.6 m/s

(b) In elastic collision, we have;

[tex]K.E._{itennis}[/tex] + [tex]K.E._{ibasketball}[/tex] = [tex]K.E._{2tennis}[/tex] + [tex]K.E._{2basketball}[/tex]

Which gives;

0.5·m₁·u₁² + 0.5·m₂·u₂² = 0.5·m₁·v₁² + 0.5·m₂·v₂²

Where;

u₂ = -v₂

Therefore;

m₁·u₁ + m₂·u₂ = m₁·v₁ + m₂·v₂

Using the formula for head on elastic collision, we get;

u₁ = The initial velocity of the tennis ball before collision

u₂ = The initial velocity of the basketball before collision

v₁ = The velocity of the tennis ball after collision

v₂ = The velocity of the basketball after collision

[tex]v_1 = \dfrac{m_1 - m_2}{m_1 + m_2} \cdot u_1 + \dfrac{2 \cdot m_2}{m_1 + m_2} \cdot u_2[/tex]

Which gives;

[tex]v_1 = -\dfrac{25}{29} \cdot u_1 - \dfrac{1242}{145}[/tex]

[tex]v_2 = \dfrac{2 \cdot m_1}{m_1 + m_2} \cdot u_1 - \dfrac{m_1 - m_2}{m_1 + m_2} \cdot u_2[/tex]

Which gives;

[tex]v_2 = \dfrac{4}{29} \cdot u_1 - \dfrac{115}{29}[/tex]

Taking the initial velocity of the tennis ball to be equal and opposite to the

initial velocity of the basketball, we have;

u₁ = 4.6 m/s

Which gives;

[tex]v_1 = -\dfrac{25}{29} \times 4.6- \dfrac{1242}{145} \approx -12.53[/tex]

The initial velocity of the tennis ball upwards, v₁ ≈ 12.53 m/s

The height to which the ball rebounds, [tex]h= \dfrac{v_1^2}{2 \cdot g} = \dfrac{12.53^2}{2 \times 9.81} \approx 8[/tex]

The maximum height to which the tennis ball rebounds, h ≈ 8.0 meters

Learn more here:

https://brainly.com/question/18432099