Question

a) A girl with a mass of 45 kg is standing on a scale in a lift. What is the weight of the girl when (i) the lift is accelerating upwards at 2.0 ms s −2 and (ii) the lift is moving down with a constant velocity. Calculate the inertial force in each case. (5) b) An object is being rotated in a centrifuge which has a radius of 6.0 m. If the acceleration of the centrifuge is 3 g, calculate the velocity of object and the time period of its motion.

Answer 1

Hi Friend,

When the lift moves upwards,the new force acts with the net force.

=mg +ma

=m(g+a)

=60(10+2)

=60(12)

F=720 N

When the body acts against the gravity, the new force tends to decrease the net force.

=m(g-a)

= 60(10-2)

=60(8)

F=480N

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