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During an ice show a 60 kg skater leaps into the air and is caught by an initially stationary 75.0 kg skater.a. What is their final velocity assuming negligible friction and that the 60.0-kg skater's original horizontal velocity is 4.00 m/s?b. How much kinetic energy is lost?

Respuesta :

Answer:

(a). The final velocity is 1.78 m/s.

(b). The lost kinetic energy is 266.13 J.

Explanation:

Given that,

Mass of first skater = 60 kg

Mass of second skater = 75.0 kg

Initial velocity = 4.00 m/s

(a). We need to calculate the final velocity

Using conservation of momentum

[tex]m_{1}u_{1}+m_{2}u_{2}=(m_{1}+m_{2})v[/tex]

Put the value into the formula

[tex]60\times4.00+75.0\times0=(60+75.0)v[/tex]

[tex]v=\dfrac{60\times4.00}{60+75}[/tex]

[tex]v=1.78\ m/s[/tex]

The final velocity is 1.78 m/s.

(b). We need to calculate the lost kinetic energy

Using formula of kinetic energy

[tex]\Delta E=E_{2}-E_{1}[/tex]

[tex]\Delta E=\dfrac{1}{2}(m_{1}u_{1}^2+m_{2}u_{2}^2)-\dfrac{1}{2}(m_{1}+m_{2})v^{2}[/tex]

[tex]\Delta E=\dfrac{1}{2}(60\times4^2)-\dfrac{1}{2}\times(60+75)\times1.78^2[/tex]

[tex]\Delta E=266.13\ J[/tex]

Hence, (a). The final velocity is 1.78 m/s.

(b). The lost kinetic energy is 266.13 J.

a. The final velocity should be considered as the 1.78 m/s.

b. The lost kinetic energy  should be considered as the 266.13 J.

Conservation of momentum:

Since

Mass of first skater = 60 kg

Mass of second skater = 75.0 kg

Initial velocity = 4.00 m/s

a.

We know that

[tex]mm1v1 + m2v2 = (m1 + v1)v\\\\60*4.00 + 75*0 = (60 + 75)v[/tex]

v = 60 + 4/60 + 75

= 1.78 m/s

b.

[tex]E = 1/2(m1v1^2 + m2v2^2) - 1/2(m1 + vm2)v^2\\\\= 1/2(60*4^2) - 1/2 * (60 + 75)*1.78^2[/tex]

= 266.13 J

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