how do i find the mass of an object with 3m/s

Question

anonymous · Answer

Only velocity is given??

anonymous · Answer

yes

anonymous · Answer

this is the question "A children's roller coaster is released from the top of a track, if its maximum speed at ground level is 3 m/s. find the height that its released from.

raffle_snaffle · Answer

kinetic energy

mrnood · Answer

you do not need the mass

At the 'ground level' it has a speed of 3 m/s which gives it a KE of 0.5 mv^2

At the top of the track it has a PE of mgh 

The PE is converted to PE when it rolls down so:

mgh = 0.5mv^2   and you can see that the mass cancels out

h=0.5v^2/g

anonymous · Answer

@jose8787

u=0 m/s
v=3 m/s
a=g=9.81 m/s^2
$$v ^{2}=u ^{2}+2as $$
$$s=v ^{2}/2g$$
s=h= 9/s*9.81
s=.45 m