When you subtract and add what is in the parentheses you would get -15 so I’m guessing he didn’t go from left to right when working inside the parentheses but when you solve the whole problem out you would get the answer: -41.25 If I missed something or you need me to show the work just let me know but I hope this helps !
Answer:
Our equation for the height is:
y(t) = 275 - 16*t^2.
a) To find the average velocity between two times, t1 and t2, (where t2 > t1) the equation is:
Then:
i) t1 = 4s, t2 = 4s + 0.1s = 4.1s
The average velocity is:
And the units will be ft/s, so the average speed is:
-129.6 ft/s
The minus sign is because te pebble is falling down.
ii) t1 = 4s, t2 = 4s + 0.05s = 4.05s
The average velocity is:
So the average speed is -128.9 ft/s
iii) t1 = 4s, t2 = 4s + 0.01s = 4.01s
The average speed is:
The average speed is -128.16 ft/s.
b) The instantaneous velocity of the pebble after 4 seconds can be obtained by looking at the velocity equation, that is the derivative of the height equation.
v(t) = dy(t)/dt.
v(t) = -2*16*t + 0
Then the velocity at t = 4s is:
v(4s) = -32*4 = -128
The instantaneous velocity at t = 4s is -128 ft/s.
The answer is 20/72 or 5/18
It would be answer D your welcome
Answer:
D - The elevator traveled upward at a rate of 2(2/5) feet per second.
Step-by-step explanation:
Okay, this is almost like kinematics, which deals with physics.
Here are your given values:
Position 1 = 70ft [down]
Position 2 = 10ft [down]
Change in time (Δt - time - scalar) = 25 seconds
The equation for displacement is d₂-d₁. This would be the change of position of the elevator during the 25 seconds.
So, we can use this equation to figure out the change in position.
Δd = d₂-d₁ = 10ft [down] - 70 ft [down] = 60ft [up]
The equation for velocity is Δd/Δt. This would be the rate of which the elevator travels. Velocity is simply speed but with a direction.
So, we can use this equation to solve.
v = Δd / Δt = 60 feet [up] / 25 seconds = 2.4 ft / second [up].
Now, we need to change 2.4 ft / second [up] into a fraction.
2.4 -> 2 (4/10) -> 2 (2/5)
All I am simply doing is figuring out the distance the elevator traveled and determined the direction of which the elevator traveled. Then, I divided that by the time the elevator traveled to determine its speed and the direction the elevator traveled.
