Question

17) During the first half of a 2.0 mile bike race with a friend of yours, your friend bikes the whole way at a constant speed of 22 mi/hr. You start from rest and accelerate constantly from the beginning. You both are neck-and-neck at the half-way point of the race. What was your acceleration rate? Answer: Not yet correct, tries 1/35 Hint: What kind of diagram(s) might help you analyze this question? Do you need calculus to solve this problem? 18) For the second half of the race, you maintain the same speed you had at the half-way point. How much faster does your friend need to bike in order to tie with you at the end of the race (assume that they pick up their pace very quickly and so you can think of them as moving at a constant speed for pretty much the entire second half of the race)? Answer: 19) Assuming your friend does tie with you at the end. What was her average acceleration over the time interval of the entire race? Answer: Not yet correct, tries 0/35

Answer 1

17)   

During half the race, distance cover by them , s= 2/2=1miles

time to travel the half the distance by your friend= (1/22) hr.

now since you are reaching at the same time to half of the race. time of travel for you will be also same(1/22 hr)

for you distance travelled equation, will be

since, you starts from rest so, u=0

t=1/22 and s=1mile

mil/hr^2

18) your speed after 1/22 hr of acceleration, will be

?

since, your friend speed is 22 mil/hr, so he has to make 44 mil/hr at start of the second half of the race to tie the race,

mil/hr

so he has to increase his speed by 22 mil/hr to tie the race.

19) your speed is constant=44 mil/hr

so time to complete the second half of race by you = 1/44 hr

assume your friends average acceleration is 'a' overal the whole race.

total time of race =(1/22 +1/44)=3/44

using equation

for second half race, for your friend initial velocity, u=22 mil/hr and t= 1/44 hr and s=2 mil