Newtons second law of motion: "T<span>he acceleration of an object as produced by a net force is directly proportional to the magnitude of the net force, in the same direction as the net force, and inversely proportional to the mass of the object."

kinetic energy is energy that an object posses while in motion and to get that it must have potential energy.</span>

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3 years ago

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A skater has rotational inertia 4.2 kg.m2 with his fists held to his chest and 5.7 kg.m2 with his arms outstretched. The skater

Fynjy0 [20]

Answer:

6.13428 rev/s

Explanation:

$I_f$ = Final moment of inertia = 4.2 kgm²

I = Moment of inertia with fists close to chest = 5.7 kgm²

$\omega_i$ = Initial angular speed = 3 rev/s

$\omega_f$ = Final angular speed

r = Radius = 76 cm

m = Mass = 2.5 kg

Moment of inertia of the skater is given by

$I_i=I+2mr^2$

In this system the angular momentum is conserved

$L_f=L_i\\\Rightarrow I_f\omega_f=I_i\omega_i\\\Rightarrow \omega_f=\dfrac{I_i\omega_i}{I_f}\\\Rightarrow \omega_f=\dfrac{(5.7+2\times 2.5\times 0.76^2)3}{4.2}\\\Rightarrow \omega_f=6.13428\ rev/s$

The rotational speed will be 6.13428 rev/s

5 0

3 years ago