## Finding the speed of a bicycle

1. The problem statement, all variables and given/known data
Two physics students are trying to detemine the
instantaneous speed of a bicycle 5.0 m from the
start of a 1000 m sprint. It takes 4s to travel 10m. What is the instananeous speed at the 5m mark? acceleration is constant.
(5m mark is 10 m as they start at -5m)
X=Distance
U=initial speed (U= 0m/s)
Note. This is the first thing ive tried since joining year 11 so i am quite a novice and may have just made a stupid error

2. Relevant equations
X=ut+1/2at^2
V=U+at

3. The attempt at a solution
x=ut+1/2at^2
10=(1/2).(a).(16)
10=8.a
a=1.25

V=u+at
V=(1.25)(4)
V=5m/s

But the answers say it 3.5m/s.
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution

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 Your acceleration is correct and you used the equation correctly except for the second part. The time t=4s is for 10m displaced not for 5m. So, let's look at the given: a = 1.25 m/s^2 Vo = 0 Vf = ? displacement = 5m. Note: You have three given, so you should be able to solve for Vf (instantaneous speed).
 you are right

 Tags easy, easy question, speed