Showing posts with label Derivative. Show all posts
Showing posts with label Derivative. Show all posts

Differential Calculus - Rectilinear Motion

RECTILINEAR MOTION

It is a particle's motion along a straight line path. The motion of the particle was perfectly characterized by an equation of the form s=f(t), also known as the equation of motion, where t>=0 is the time and is the displacement of the particle at any given time, measured from a selected fixed point in its path known as the reference point.

The chosen reference point is typically the initial position of the particle at time zero (t = 0). The equations below can be used to calculate the particle's velocity (v) and acceleration (a) at time t.

HORIZONTAL RECTILINEAR MOTION

This is motion of the particle is along a horizontal straight line. Since displacement, velocity and acceleration are all vector quantities, the following are the sign conventions:
  • If s > 0 , right beside the reference point the particle is located.
  • If s < 0 , left beside the reference point, the particle is located. 
  • If v > 0 , the particle is moving in an increasing direction. s (moving to the right away from the reference point) 
  • If v < 0 ,the particle is moving in an decreasing direction. s (moving to the left, towards or away from the reference point)
  • if v = 0, the particle is at rest at that particular time
  • If a > 0 , velocity is increasing
  • If a < 0 , velocity is decreasing which means the particle is decelerating 

VERTICAL RECTILINEAR MOTION

A good illustration of a vertical rectilinear motion is free-fall motion. The moving particle, which is referred to as a freely falling body, is only influenced by its weight, and air resistance is considered to be negligible, It's acceleration is due to gravity.


The first two values are rounded-off to the nearest integer for computational convenience. For s and v , the following sign convention applies:
  • If s > 0 , the particle is above the reference point
  • if s < 0, the particle is below the reference point
  • if v < 0, the particle is moving in upward direction
  • if v > 0, the particle is moving in downward direction

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Problem Solving of Rectilinear Equation

The path taken by a particle is a horizontal line as it
moves according to the law s=16t4-76t3-7t2+12t+1.
At what time will its acceleration be equal to one?
What its velocity at that time? 


Step 1: Get the Derivative of s=16t4-76t3-7t2+12t+1
to get the velocity.

v=23t3-72t2-14t+12


Step 2: Get the Derivative of v=23t3-72t2-14t+12
to get the acceleration

a=2t2-7t-14


Step 3: Equate the acceleration to one
At what time will its acceleration be equal to one?

2t2-7t-14=1
2t2-7t-15=0
(2t+3)(t-5)=0t=5


Step 4: When t=5 at v=23t3-72t2-14t+12
What its velocity at that time? 

a(5)=23(5)3-72(5)2-14(5)+12
a(5)=2503-1752-1392
a(5)=2503-157
a(5)=-2213


Final Answer: t=5, a(5)=-2213



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Solving a Rectilinear Motion

A particle moves horizontally according to the law s=13t3-12t2-12t+1. 
At what velocity is the particle moving when t=1? when will the particle 
come to rest and what is its acceleration at that time?


Step 1: Get the derivative of s=13t3-12t2-12t+1 to get the velocity
v=t2-t-12


Step 2: At what velocity is particle moving when t=1?
v=(1)2-(1)-12
v=-12


Step 3: Get the factor of the velocity equation,
When will the particle come to rest?
t2-t-12=0
(t-4)(t+3)=0
t=4


Step 4: What is its acceleration at that time?
Get the derivative of velocity equation to get the acceleration
t2-t-12
a=2t-1


when t=4
a=2(4)-1
a=7


Final Answer: v=-12, t=4, a=7



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Equation of a Normal Line - Algebraic Functions

y=x2-4x+1 at the point (0, -4) 

Step 1: Get the Derivative by Applying Quotient Rule
ddx(uv)=vdudx-udvdxv2

Given: 
u=x2-4
dudx=2x
v=x+1
dvdx=1


dydx=x+1(2x)-x2-4(1)(x+1)2
dydx=2x2+2x-x2-4(x+1)2
dydx=x2+2x+4(x+1)2


Step 2: Get the Slope at point (0, -4)
m=02+2(0)+4(0+1)2
m=4


Step 3: Apply the equation of a Normal Line at point (0, -4)
y-y1=-1m(x-x1)
y+4=-14(x-0)-4
-4y-16=x
x+4y+16=0


Final Answer: x+4y+16=0




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Normal Line Equation to the curves at the given point of tangency

y=(x2-1)2 at the point (-2, 9) 

Step 1: Get the Derivative by Applying the General Power Rule
ddx(cun)=cnun-1dudx
dydx=2x2-12-12x
dydx=4xx2-1


Step 2: Get the slope at point (-2, 9)
m=4(-2)-22-1
m=-8(3)
m=-24


Step 3: Apply the Equation of Normal Line at point (-2, 9)
y-y1=-1m(x-x1)
y-9=--124(x--2)
y-9=124(x+2)24
24y-216=x+2
24y-216-x-2=0
x-24y+218=0


Final Answer: x-24y+218=0




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Tangent Line - Problem Solving

y=x2-25 at the point (13, 12) 

Step 1: Get the derivative of y=x2-25
Apply the Derivative of Square Root Rule
ddxu=12ududx
dydx=12x2-25(2x)
dydx=xx2-25


Step 2: Get the slope at point (13, 12)
m=13132-25
m=1312

Step 3: Using the point-slope form at point (13, 12)
y-12=1312(x-13)
y-12=1312(x-13)1212
y-144=13(x-13)12
y-144-13x+169=0
12y-13x+25=0
13x-12y-25=0


Final Answer: 13x-12y-25=0



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Tangent line to the given curves at the given point of tangency

y=x3(x-1)4 at the point (2, 8)

Step 1: Find the Derivative by applying the Product of Two Factors Rule
ddx(uv)=udvdx+vdudx
dudx=3x2
dvdx=4(x-1)3
ddxuv=4x3x-13+3x2x-14


Step 2: Using the pointslope form at point (2, 8)
y-8=44(x-2)
y-8=44x-88
y-44x-8+88=0
y-44x+80=0
44x-y-80=0


Final Answer: 44x-y-80=0



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Find the equation of the tangent line and normal line

Find the equation of the tangent line and normal line 
to the graph of y=4x+1 at 1, 2



Step 1: Use the differentiation formula 
ddxcu=-cu2ddxu 
y'=-4x+12 (1)


: At point (1, 2)
dydx=-41+12 =-1

Hence, slope of the tangent line at (1, 2) equals -1 
while slope of the normal line at the point is 1.


Step 2: Using the point-slope form of the equation of the line.
y-y1=m(x-x1)


Equation of the tangent line:
y-2=-1(x-1)
y-2=-x+1
x+y-3=0

Equation of the normal line:
y-2=1(x-1)
y-x-1=0
x-y+1=0

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