A sprinter explodes out of the starting block with an acceleration of +4.5 m/s2, which she sustains for 0.9 s. Then, her acceleration drops to zero for the rest of the race.
(a) What is her velocity at t = 0.9 s.
(b) What is her velocity at the end of the race?
(a) What is her velocity at t = 0.9 s.
(b) What is her velocity at the end of the race?
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(a) 4.5(.9s)= 4.05m/s
(b) 4.05 m/s, 0 acceleration means that a constant speed is maintained.
(b) 4.05 m/s, 0 acceleration means that a constant speed is maintained.
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If her acceleration is 4.5 m/s2 that means that every second, she is going 4.5 m/s faster. at 0.9 seconds she will be moving at 4.05* meters per second and since she stops accelerating at .9 seconds she keeps that velocity for the rest of the race.
*(4.5 x 0.9)
*(4.5 x 0.9)
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a. V = 4.5(0.9)
b. V = 4.5(0.9) (since there is no acceleration after, there is no change in velocity for the rest of the race.)
b. V = 4.5(0.9) (since there is no acceleration after, there is no change in velocity for the rest of the race.)