one type of aeroplane has a maximum acceleration on the ground of 3.5ms-2(adsbygoogle = window.adsbygoogle || []).push({});

a)for how many seconds must it accellerare along a runway in order to reach its take-off speed of 115ms-1?

b) what is the minimum length of runway needed for it to reach this length?

ummm, not entirely sure

av acceleration=total change in velocity/time taken

speed=distance/time

for a) i thought that it might be 115/3.5 which gives 82.86 (4 sig fig)

but then b) i thought maybe v=d/t

so 3.5=115/x

but that obviosly comes out to 115/3.5 and so the same answer, i don't really know which i have write, if either.

also i have a question about a baby carriage on a ramp

it accellerates at an average rate and takes 15s to reach the bottom of a 5m ramp.

i got that the average velocity is 15/5= 3m/s

but i need to work out the velocity at the bottom of the ramp and then the average acceleration. I can quite happily get the acceleration if i can find the final velocity, but i don't really know. i thought that as the acceleration was uniform the final velocity might be 6m/s, but this doesn't seem right

thanks

resresd

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# Homework Help: Accelleration and dispacement of planes and babiess

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