Velocity of an object sliding down a ramp at a certain point?

I recommend using the energy approcah:

When the body is standing at the top of the ramp, it has gravitational potential energy:

E=mgH

When it begins to slide, the energy slowly converts to kinetic energy, but if the body is at some height(hasn't reached the ground yet), for example 0.5H, it still has some gravitational energy. So, the equation to work with is:

mgH=mv^2/2+mgh

since you need the velocity, you get the following:

v=sqrt(2g(H-h))

if you want to express the distance, by distance along the ramp (from the end of the ramp), not by height, the expresion becomes:

v=sqrt(2g(H-d*sin(angle_of_the_ramp)))

where H is the highest point of the ramp, d is distance from some point on ramp, to ground, but distance measured along the ramp.

Im not sure about question but i would use conservation of energy...

KEi + PEi = KEf + PEf

Initially Ke would be 0 (assuming) and PE is given by mgh

then as it slides downt hte ramp PE is converted to PE

so mgh=0.5mv^2

question no2. learn that our earth that planet having very low gravitational acceleration. So, that pendulam peroid could be under T. question 4. rigidity 2F will stretch this spring to a distance of x<. greater advantageous than x.