Amass is suspended from the roof of a lift (elevator) by means of a spring balance. the lift (elevator) is

moving upwards and the readings of the spring balance are noted as follows:

speeding up: ru constant speed: rc slowing down: rd

which of the following is a correct relationship between the readings?

(a) ru  rc (b) ru = rd (c) rc < rd (d) rc  rd

A0.580-kg rock is tied to the end of a string and is swung in a circle with a radius of 0.500 meters. the velocity of the rock is 4.50 m/s. what is the centripetal force acting on the rock? 15.5 n 5.22 n 69.8 n 23.5 n

The man of mass m1 and the woman of mass m2 are standing on opposite ends of the platform of mass m0 which moves with negligible friction and is initially at rest with s = 0. the man and woman begin to approach each other. derive an expression for the displacement s of the platform when the two meet in terms of the displacement x1 of the man relative to the platform.

You can decrease the resistance of a length of wire by