Posted by eric on Monday, August 8, 2011 at 2:36am.
A student driver is travelling at 22.2 m/s and sees a school zone ahead. Using her brakes, she accelerates at 2.8 m/s2 to reduce her velocity to 8.2 m/s. How much time did it take to change her velocity?

science 10  drwls, Monday, August 8, 2011 at 5:53am
(deceleration rate)*(time) = (speed change)
She reduces her speed by 14 m/s, so the change is 14 m/s.
time = (14 m/s)/(2.8 m/s^2)
= 5 seconds

science 10  YASH, Monday, August 8, 2011 at 1:15pm
u=22.2m/s
a=2.8m/s2
v=8.2m/s
t=?
v=u+at (equation)
8.2=22.2+(2.8)t
8.222.2=2.8t
14=2.8t ('' sign is cancelled from both the sides)
14/2.8=t
5=t
hence time taken is 5 seconds
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