vi is going in the positive direction (up). (That's my choice). a (acceleration) is going in the minus direction (down). The directions could be reversed.
Givens
vi = 160 ft/s
vf = 0 (the rocket stops at the maximum height.)
a = - 9.81 m/s
t = ????
Remark
YOu have 4 parameters between the givens and what you want to solve. Only 1 equation will relate those 4. Always always list your givens with these problems so you can pick the right equation.
Equation
a = (vf - vi)/t
Solve
- 32 = (0 - 160)/t Multiply both sides by t
-32 * t = - 160 Divide by -32
t = - 160/-32
t = 5
You will also need to solve for the height to answer part B
t = 5
vi = 160 m/s
a = - 32
d = ???
d = vi*t + 1/2 a t^2
d = 160*5 + 1/2 * - 32 * 5^2
d = 800 - 400
d = 400 feet
Part B
You are at the maximum height. vi is 0 this time because you are starting to descend.
vi = 0
a = 32 m/s^2
d = 400 feet
t = ??
formula
d = vi*t + 1/2 a t^2
400 = 0 + 1/2 * 32 * t^2
400 = 16 * t^2
400/16 = t^2
t^2 = 25
t = 5 sec
The free fall takes the same amount of time to come down as it did to go up. Sort of an amazing result.
Answer:
15 inches.
Step-by-step explanation:
V = 1/3 pi r^2 h
7065 = 1/3 * 3.14 * 30 * r^2
r^2 = 7065 / (1/3 * 3.14 * 30)
r^2 = 7065 / 31.4 = 225
r = sqrt 225 = 15.
Answer:
Step-by-step explanation:
5.
12x-7
12 x 4-7
48-7=41
answer-41
6.
(4 to the power of 2 =16)
16 divided by 8=2
answer-2
7.
5(1) + 3(7)-1(to the third power)
exponents first-1
multiplication
5x1=5 + 3x7=21
21+5=26
26-1
answer-25
8. 8(2nd power)divided by 2(4) +3(7)-1
8 to the 2nd power =16
2(4)=8
3(7)=21
16 divided by 8+21-1
8+21=29
29-1=28
answer 28
Answer:
D. 343 3/4
Step-by-step explanation:
1 inch = 125 miles
There is a distance of 2 3/4 inches
The first thing you would do is double 125, since it is one inch, and 2 inches would another 125. Now you have 250. To get the rest, you would need to divide 125 by 4, getting 31.25. Now since the question needs 3/4 of 125, you multiply 31.25 by 3, which is 93.75. Now add 250, and 93.75. You get 343.75, or 343 3/4
