Originally Posted by

**justin016** A raindrop has an initial downward speed of 10m/s and its downward acceleration a is given by

a= { 9-0.9 if 0<=t<=10 or 0 if t>10}

a. How far does the raindrop fall in the first 10s

b. What is the velocity of the raindrop after 1s Mr F says: There is a typo in the book. The question is meant to ask for velocity after **10s**.

c. If the raindrop is initially 600m above the ground, how long does it take to fall?

Here is what ive done so far

a(t)=9-0.9t

v(t)=9t-0.45t^2+10

h(t)=4.5t^2-0.15t^3+10t

a. h(10)=4.5(10)^2-0.15(10)^3+10(10)= 400m

which is correct

b. v(1)=9(1)-0.45(1)^2+10 = 18.55 m/s

the answer is 55m/s. Is there something wrong here?

c. Since 600m > 400m, then it takes more than 10s to fall

a(t)=0

v(t)=10

h(t)=10t+600

0=10t+600

t= -60s ?

the answer is 13.6s

What did i do wrong for b and c?