Trajectory problems??????

Question

two balls A and B are thrown from a running train.Ball A is just dropped while B is thrown horizontally outwards.which of these bodies will reach the ground earlier??

also when a cyclist taking a turn bends inward while a car passenger taking the same turn is thrown outward by it.whats the rason?

ok n last one

a stone is whirled in a vertical circle at the end of a string.when the stone is at its heighest position,the tension in the string will be:

1.Equal to the weight of stone

2.less than the weight of stone

i know the answer of this question but i dont know the reason so plzz do tell

Answer 1

i can only answer the first question immediately, i'll have to think about the others. the two balls will reach the ground at the same time if air resistance is considered to be negligible as both balls accelerate vertically at the same rate and so take the same amount of time to reach the ground. you take the horizontal motion and vertical motion to be separate.

Answer 2

Both'll reach the ground at d same time since the vertical component of the initial velocity for both is 0. Also.the other conditions are d same. d answer of d 2nd one is that whena cyclist takes a turn,the centripetal force is more dominant than d centrifugal force but in d other case the latter dominates over the former.

the answer of the 3rd one is this--at the highest posn. of stone, Tension  in the string is  upwards but due to gravity, weight acts downwards. Thus.net Tension in the string==mg  -   (m*v^2)/r      which is of course less than the wight of d body