# Mechanics A Level Maths Question

At time T=0, particle A is dropped from a bridge 40m above the ground. One second later particle B is projected vertically upwards with speed 5ms-1 from a point 10m above the ground.
A) find the distance travelled by A when B is at the highest point in motion.
B) how long after A is dropped do the two particles become level?
C) How far from the ground are they at this time
Original post by aflowers
At time T=0, particle A is dropped from a bridge 40m above the ground. One second later particle B is projected vertically upwards with speed 5ms-1 from a point 10m above the ground.
A) find the distance travelled by A when B is at the highest point in motion.
B) how long after A is dropped do the two particles become level?
C) How far from the ground are they at this time

What have you done/tried? A sketch usually helps with the relevant info/variables made explicit.
For a) I found the time when v = 0 for ball B, which was 0.51s and then added 1 and subbed it into the equation s = ut + 1/2 at2 so I got 11m (1sf)
I was more struggling on b and c. I tried to set up simultaneous equations to find s but was struggling to work out the displacements in terms of upwards positive.
Original post by aflowers
For a) I found the time when v = 0 for ball B, which was 0.51s and then added 1 and subbed it into the equation s = ut + 1/2 at2 so I got 11m (1sf)
I was more struggling on b and c. I tried to set up simultaneous equations to find s but was struggling to work out the displacements in terms of upwards positive.

It would help to post your sketch / workings. You obviously have a time shift so B is "t-1" if A is "t" and you need to decide which is the origin and add an appropriate initial displacement onto the other. But it shouldnt be that hard to set up, so post what you tried?

Note you could get a simpler solution using relative motion/suvat, so model the motion of one particle relative to the other. But Id get the first way working first as its the usual a level way to go.
(edited 9 months ago)