a stone us thrown vertically upwards under gravity with a speed of u m/s from a point

[markosheehan]

a stone us thrown vertically upwards under gravity with a speed of u m/s from a point 30 metres above the horizontal ground. the stone hist the ground 5 seconds later.

(i) find the value if u
(i)find the speed with which the particle hits the ground.

can someone help me work this out. i tried to divide it into 2 different parts. from when the stone is thrown up to when it gets to v=0 and then from when it drops back down to earth. i tried to use uvast equations and i could say the 1st bit has time t and the next bit has 5-t time but the intial speeds are not the same so i dont know what to do

 

[Deleted member 4993]

a stone us thrown vertically upwards under gravity with a speed of u m/s from a point 30 metres above the horizontal ground. the stone hist the ground 5 seconds later.

(i) find the value if u
(i)find the speed with which the particle hits the ground.

can someone help me work this out. i tried to divide it into 2 different parts. from when the stone is thrown up to when it gets to v=0 and then from when it drops back down to earth. i tried to use uvast equations and i could say the 1st bit has time t and the next bit has 5-t time but the intial speeds are not the same so i dont know what to do

For the first stage the stone starts with a speed u, moving upwards with accn. -9.81 m/s² and the final speed = 0.

For the second stage the stone starts with a speed 0, moving downwards with accn. 9.81 m/s².

 

[stapel]

i tried to use uvast equations and i could say the 1st bit has time t and the next bit has 5-t time but the intial speeds are not the same so i dont know what to do

I'm sorry, but I don't know what this means...? What are the "uvast equations"? (This is why we ask that you show your work, rather than merely making reference to it, so that we can see what you're doing.)

a stone us thrown vertically upwards under gravity with a speed of u m/s from a point 30 metres above the horizontal ground. the stone hist the ground 5 seconds later.

(i) find the value if u
(i)find the speed with which the particle hits the ground.

They were supposed to have given you the equation for projectile motion. You can learn this information here. Once you have studied at least two lessons from the link, please attempt the exercise. If you get stuck, you can then reply with a clear listing of your thoughts and efforts so far, starting with the basic set-up explained in the lessons:

. . . . .\(\displaystyle s(t)\, =\, -9.8\, t^2\, +\, u\, t\, +\, 30\)

. . . . .\(\displaystyle s(5)\, =\, -9.8\, (25)\, +\, 5\,u\, +\, 30\, =\, 0\)

...and so forth. Thank you!