Hi everyone! I would like some help with some physics! I think im being very stupid! The question is "A cyclist travels to work at an average speed of 3ms^-1 and returns home for tea at an average speed of 9ms^-1. Caluclate her average speed for the whole journey." By the way, the answer isnt 6 ms^-1 Help! Thnx in adv.
This is most likely wrong but here goes. If it takes her 3 hours to get to work at 3ms then won't it take here one hour to get home at 9ms. Thus we now have a four hour journey. 3+3+3+9=18 (speed) divide by time (4) = 4.5ms-2.
Well, funnily enough i got 4.5ms^-1 when i had a go, so for 2 of us to get that, its likely to be the correct answer. I did it a diff way tho.
Yep, her overall DISPLACEMENT is 0, since she finishes where she started but this is asking for her average speed. How i did was: Let the distance to work = d Therefore, her total distance covered = 2d As we know, Avg. Speed = Total Distance/Total time = 2d/ [(d/3) +(d/9)] = 2d/(4 d/9) = 2 d. 9/4d = 18 d/ 4d = 4.5ms^-1
Id go with 4.5ms^-1, if it was asking about velocity it would be 0 as velocity is a vector measurement and incorporates direction, speed however takes no account of the direction of travel.
