Help maths super urgent 😭

Alevelhelp.1

I don’t get how to do this I got 10 but the ans is 23 m

plz explain I used suvat and u was 14 v was zero and a 9.8 but still I got wrong

(edited 10 months ago)

Reply 1

davros

Original post by Alevelhelp.1

I don’t get how to do this I got 10 but the ans is 23 m

plz explain I used suvat and u was 14 v was zero and a 9.8 but still I got wrong

what are your 2 suvat equations for stone 1 and stone 2?

remember that stone 2 starts 1 second later so its "t" is not the same as "t" for the 1st stone!

Reply 2

mqb2766

Using simultaneous suvats with a time offset is the standard way to go but you could think about relative motion, especially because the relative acceleration is zero (both are falling under gravity so accelerate at the same rate).

After 1 s the first stone has moved 4.9 m and has a speed of 9.8 m/s. So the second stone, relative to the first must catch up 4.9 m when the relative speed is 4.2 m/s (14-9.8) with zero rellative acceleration. So speed-distance-time gives the time until they meet and hence you can get the required height / distance moved by one of the stones in that time using the obvious suvat.