7. Two cars momentarily stopping at red light signal. At green light, both cars

Question

7. Two cars momentarily stopping at red light signal. At green light, both cars start accelerating from rest, car A with 5.0 m/s^2 and car Bat 3.0 m/s^2. (a) What is its distance between the two cars after 5.0 s. (6) What is the velocity of each car at to 5.0s. S. Upon graduation, a joyful physics student throws her cap straight upward with an initial speed of 14.7 m/S. Given that Its acceleration has a magnitude of 9.87 m/s^2 and Is directed downward (neglect air resistance), a) How long does it take the cap to reach its highest point ? b) What is the distance to the highest point? e) Assuming the cap is caught at the same height from which it was released, what is the total time the cap Is in flight?

Explanation / Answer

7)

car A travels to a distance of

s=ut+0.5at^2 (intial velocity of both cars =0 starting frm rest)

s=62.5 meters

car B travels=ut+0.5at^2

s=37.5 meters

distance between them =25 meters

b)

for car A

v=u+at

v=5*5=25m/sec

for car B=

v=u+at

v=3*5=15m/sec

8)

a)

v=u+at

v=0 as it reaches max point

t=u/a=1.4984 sec

b)

v^2-u^2=2as

v=0 as it reaches heighest point

U^2/2a=14.7*14.7/2*9.8=11.013 meters

c)

total time of flight

=1.49+1.49=2.98 seconds

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