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**1. Homework Statement**

a car accelerates at 1.5ms^-2 from 0 ms^-1 to 30 ms^-1. It then travels at a constant speed of 30 ms^-1.

2.A bike accelerates at 2.5ms^-2 from 0ms^-1 to 20 ms^-1 and then travels at a constant speed of 20 ms^-1

find the instant where there together.

(Both have the same displacement)

**2. Homework Equations**

all constant acceleration equations

**3. The Attempt at a Solution**

for part one, i can represent the distance as 300+30t.

t=(30-0)/1.5=20s

S=1/2(20)(30) + 30t= 300 +30t

for part 2.

t=(20-0)/2.5=8s

S=1/2(8)(20) + 20t= 80 + 20t

80+20t=300+30t

-220=10t

t=-22s

why is my answer coming in negative. My answer -22 is right but its negative.