Motion in a vertical plan question

OP

Original post by TarotOfMagic

S = ?
u = 35 ms^-1
v =
a = 9.8 ms^-2 (because the particle is being dropped downwards we take gravity to be positive)
t = 3s

Now, use an equation that coincides with all of our measurements: in order to find s (the displacement).

I already tried that. Like this:

S = ut + 1/2at^2
S = 35 (3) + 4.9(3^2)
S = 105 + 44.1
S = 149.5 m

But according to the answer this is wrong it should be 579.5 m

Thanks for your input though!

Reply 3

shinebrighterx

Original post by hals

a stone is dropped from the top of a tower. 3 seconds later another stone is thrown downwards from the same point at 35m/s. if they hit the ground at the same time find the height of the tower.

This is technically a mechanics 1 question but im sure the physics forum will have no trouble

the struggle is real

Reply 4

OP

Original post by u.sha

the struggle is real

Oh look we have matching avatars 😁

Reply 5

an_atheist

Original post by TarotOfMagic

S = ?
u = 35 ms^-1
v =
a = 9.8 ms^-2 (because the particle is being dropped downwards we take gravity to be positive)
t = 3s

Now, use an equation that coincides with all of our measurements: in order to find s (the displacement).

You're an idiot. The stone moving at 35 m/s is dropped 3 seconds after the first, it doesn't take 3 seconds to reach the floor.

Original post by hals

a stone is dropped from the top of a tower. 3 seconds later another stone is thrown downwards from the same point at 35 m/s. if they hit the ground at the same time find the height of the tower.

This is technically a mechanics 1 question but im sure the physics forum will have no trouble

For the first stone,
s=
u=0
v=
a=9.8
t=t+3

For the second stone
s=
u=35
v
a=9.8
t=t

Equate the two displacements to find time, then find displacement using that value of t

Reply 6

OP

Original post by an_atheist

You're an idiot. The stone moving at 35 m/s is dropped 3 seconds after the first, it doesn't take 3 seconds to reach the floor.

For the first stone,
s=
u=0
v=
a=9.8
t=t+3

For the second stone
s=
u=35
v
a=9.8
t=t

Equate the two displacements to find time, then find displacement using that value of t

Thanks
Shouldn't t=t-3 for the 1st stone because it happens before the 2nd one -.-

P.s. That idiot remark was unnecessary but ill let it slide because you tried to help

Reply 7

an_atheist

Original post by hals

Thanks
Shouldn't t=t-3 for the 1st stone because it happens before the 2nd one -.-

P.s. That idiot remark was unnecessary but ill let it slide because you tried to help

**** you are correct. Sorry about the idiot thing, it annoys me when people (inclding myself) manage to mess up easy maths based problems

Reply 8

OP

Original post by an_atheist

**** you are correct. Sorry about the idiot thing, it annoys me when people (inclding myself) manage to mess up easy maths based problems

Apology accepted lol. Obviously that 1st method i tried wouldnt have worked because t=3 was not the actual time of fall but then i didnt know wht else to do and came on here after trying that invalid method

Reply 9

an_atheist