a bicyclist in the Tour De France crests a mountain pass as he moves at 15km/h. At the bottom 4km/h farther, his speed is 75km/h. What is his average acceleration(m/s^2) while riding down the mountain?

Question

a bicyclist in the Tour De France crests a mountain pass as  he moves at 15km/h. At the bottom 4km/h farther, his speed is 75km/h. What is his average acceleration(m/s^2) while riding down the mountain?

anonymous · Answer

this is how i worked it out but it it didn't work: Vi=15km/h-->4.1m/s
V=75km/h--> 20.8m/s  and s=4km--> 4000m so 2a=(V^2-Vi^2)/s
2a=(20.8-4.1)/4000

anonymous · Answer

it is 20.8^2 & 4.1^2

ujjwal · Answer

what do you mean by "At the bottom 4km/h farther" ? Is it distance? we don't measure distance in km/h

anonymous · Answer

@rajathsbhat  thx, and @ujjwal  that was a typo..

anonymous · Answer

0.052m/s^2 ?

anonymous · Answer

okay, found the answer :)

ujjwal · Answer

congrats! but how did you find it?

anonymous · Answer

umm, well raj corrected by square mistake so:2a= (20.8^2-4.1^2)/4000
a=0.104/2=0.52m/s^2

kropot72 · Answer

@bronzegoddess a = 0.104/2 = 0.052 ms^-2