Someone had attempted to assist me, but the answers and work were not right. Sti
ID: 583530 • Letter: S
Question
Someone had attempted to assist me, but the answers and work were not right. Still very confused. Could someone please help me? Thanks!
You go for run with your friend. You agree to race each other, running north for 3 miles. For the first half mile, you are going twice as fast as she is. She then picks up her pace, catching up to you right at the end, after a total of about 27 minutes of running.
10[Q]) Which list of quantities is most correct?
A) Your time to the half mile mark was 3.50 min.
B) Your friend reached the half mile mark after 9.00 min.
C) You were ahead by about 402.25 meters when you reached the first half-mile.
D) After your friend quickens her pace, her new speed was 0.12 mi/min.
E) Your friend's average velocity can be expressed as 0.11i^0.11i^ mi/min.
11[C]) Suppose that the following day you and your friend run another 3 mile race, this time running half of the race straight north, and then the other half back to where you began. The race plays out identically to the previous day. Pick the statements that are true.
A) On a position-time chart that simultaneously plots both you and your friend's run, there are less than two points where your graph contacts your friend's graph.
B) Your friend's position-time graph has a constant slope during the first mile of the race.
C) Your friend's average velocity over the whole race's time interval is non-zero.
D) Your displacement over the entire period of the race is 0 miles.
E) The slope of your position-time graph switches sign after you reach the 1.5 mile mark.
Explanation / Answer
total distance travelled = 3 miles
your friend's speed ( for the first half mile) = V
your speed ( for the first half mile) = 2V
total time t = 27 min (for both of you)
for you t = 3 / 2V
for your friend t = 0.5 / V + 2.5 / V1
Hence 1 / V = 5 / ( 2 V1 )
that is V1 = 2.5 V
since V = 1 / 18 miles /min
V1 = 5 / 36 miles / min
your speed = 2V = 1/9 miles / min
you reach 0.5 mile mark at time 0.5 / (1/9) = 4.5 min statement Q10.A is wrong
your friend reach 0.5 mile mark at time 0.5 / (1/18) = 9 min statement Q10.B is right
when you reached the half mile mark, your friend was at 1/4 mile mark that is you are ahead by 1/4 mile = 402.25 m statement Q10 C is correct.
After first half mile your friend's speed = 5/36 miles /min = 0.139 miles /min statement Q10 D is wrong.
your friend's average velocity = 3 miles / 27 min = 1/ 9 miles /min = 0.111 mile /min Statement Q10 E is correct
Q11
your displacement over the entire race is zero miles statement Q11 D is correct
since displacement is zero, average velocity is zero for you and your friend. statement Q11 C is wrong
during the first half of race, slope of your graph is 1/9. In the second hallf it is negative of the above value.
statement Q11 E is correct
since your friend is running with constant velocity during first half mile her position-time graph has constant slope.
statement Q11 B is correct
the position-time graphs are straight line they cut only once when you are coming back and she is going ahead statement Q11 A is correct
Related Questions
drjack9650@gmail.com
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.