1. A particle mass attached to one end of a light spring is executing SHM on a smooth horizontal table. If another identical particle is attached to the other end of the spring, what is the period of oscillation? I don't know how to figure this problem out....I used to deal with a spring fixed to the wall only....please help!! 2. A pendulum is set to swing with an amplitude of 4cm and a period of 0.8s. The mass of the pendulum bob is 0.5kg. Calculate the tension in the string when the bob is at the lowest position. I set the equation as: F = T-mg, as F is net force pointing towards the centre, T is tension.........T= F+mg.....T= mv^2/r + mg.....T = m(w^2 *A + g)........T = 0.5 ( (2pi/0.8)^2 *0.004 + 10)........T = 6.23N But it is wrong...can anyone tell me why? 3. When a ball hits the ground, acceleration-time graph <a> is drawn....and if some kinetic energy is lost, that means the ime for the upward flight decreases. another acceleration-time graph <b> is drawn...But why <a> and <b> is the same? I suppose for graph <b>, the time duration in the rebounce( contaction with the ground) is longer, isn't it? Any help would be appreciated.