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:
C. 7 hours
Step-by-step explanation:
Let the time for the trip out be represented by t. Then the time for the return trip is t-1. The distance was the same for both trips, so we have ...
distance = speed × time
300t = 350(t -1)
300t = 350t -350 . . . . eliminate parentheses
350 = 50t . . . . . . . . . . add 350-300t
7 = t . . . . . . divide by 50
The trip out took 7 hours.
Answer:
C. 
Step-by-step explanation:
Let x be the total monthly sales.
We have been given that a salesperson earns a salary of $700 per month plus 2% of the sales. The salesperson want to have a monthly income of at least $1800.
This means that 700 plus 2% of total monthly sales should be greater than or equal to 1800. We can represent this information in an equation as:
Let us solve our inequality to find the monthly sales (x).
Subtract 700 from both sides of our inequality.
Divide both sides of inequality by 0.02.
Therefore, the total monthly sales must be greater than or equal to 55,000 and option C is the correct choice.
If you'd graph this function, you'd see that it's positive on [-1.5,0], and that it's possible to inscribe 3 rectangles on the intervals [-1.5,-1), (-1,-0.5), (-0.5, 1].
The width of each rect. is 1/2.
The heights of the 3 inscribed rect. are {-2.25+6, -1+6, -.25+6} = {3.75,5,5.75}.
The areas of these 3 inscribed rect. are (1/2)*{3.75,5,5.75}, which come out to:
{1.875, 2.5, 2.875}
Add these three areas together; you sum will represent the approx. area under the given curve on the given interval: 1.875+2.5+2.875 = ?
Answer:
there are no statements...
