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?