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:
1800
Step-by-step explanation:
there are 60 seconds in a minute
so, 30 * 60 = 1800
Let's take a look at the first few numbers in the sequence based on the given rule:
Inspecting this pattern it seems like the power
is being raised to is always one less than the number of the sequence, so if we were on the nth number in the sequence, that part of the expression would be
. We also know that we'll be multiplying whatever we get from that by 6, so we can write the full explicit rule for our sequence as
Where
is the nth number in our sequence.
Answer:
Step-by-step explanation:
cos 225 = -cos 45 = -1/√2.
sin 225 = -sin45 = -1√2.
Answer:
75 hours
Step-by-step explanation:
16 times x=1200 or
16x=1200
divide both sides by 16
1200/16
so we simplify 1200/16 by factoring out the ones (4/8=1/2 times 4/4 since 4/4=1)
1200=3*2*2*2*2*5*5
16=2*2*2*2*1
so we notice that there are four 2's in both so those are the 'ones' so cross them off and get
3*5*5/1 or 75/1 or 75 hours
