Answer:
x = -5 sin (2t)
Step-by-step explanation:
k is the spring stiffness. The unstretched length of the spring is L.
When the mass is added, the spring stretches to an equilibrium position of L+s, where mg = ks. When the mass is displaced a distance x (where x is positive if the displacement is down and negative if it's up), the spring is stretched a total distance s + x.
There are two forces on the mass: weight and force from the spring. Sum of the forces in the downward direction:
∑F = ma
mg − k(s + x) = ma
mg − ks − kx = ma
Since mg = ks:
-kx = ma
Acceleration is second derivative of position, so:
-kx = m d²x/dt²
Let's find k:
F = kx
400 = 2k
k = 200
We know that m = 50. Substituting:
-200x = 50 d²x/dt²
-4x = d²x/dt²
d²x/dt² + 4x = 0
This is a linear second order differential equation of the form:
x" + ω² x = 0
The solution to this is:
x = A cos (ωt) + B sin (ωt)
Here, ω² = 4, so ω = 2.
x = A cos (2t) + B sin (2t)
We're given initial conditions that x(0) = 0 and x'(0) = -10 (remember that down is positive and up is negative).
Finding x'(t):
x' = -2A sin (2t) + 2B cos (2t)
Plugging in the initial conditions:
0 = A
-10 = 2B
Therefore:
x = -5 sin (2t)
Answer:
y = - x - 4
Step-by-step explanation:
A line perpendicular to the line: y = x + 5
must have a slope that is the "opposite of the reciprocal" of the slope of the given line. Then the slope of the perpendicular line must be "-1".
Now that we know the slope of the perpendicular line, we use the point (-7, 3) to complete the equation of the line:
y = -1 x + b
3 = -1 (-7) + b
then we solve for "b":
3 = 7 + b
3 - 7 = b
b = -4
Now we can write the total equation of the perpendicular line in slope-intercept form as:
y = - x - 4
Answer:
b^5
Step-by-step explanation:
b^ -6 * b^11
We know that a^c * a^d = a^ (c+d)
b^ -6 * b^11 = b^(-6+11)
= b^(5)
15p^2q^2 because you multiply the coefficients and the vaiables. 3x5 is 15, pxp is p^2, and qxq is q^2
Answer:
It's all about the brackets.
Step-by-step explanation:
If we do (-4)^2, the brackets make it -4 x -4 and the two negatives make a positive of 16.
If we do -4^2, that means that the 4 is squared before putting the minus sign there so you have 4x4 = 16 then put the minus to get -16.
Hope this helps!
treviglaslibrary
