A particle starts from the origin at t=0 with an initial velocity of 5.0 m/s along the positive "x" axis. if the acceleration is: a = (-3.0i+4.5j) m/s ; determine the velocity and position of the particle at the moment it reaches it's maximum "x" coordinate.

Respuesta :

The relevant equation to use in this case is:

v = u + at                                                                              ---> 1

where v is final velocity, u is initial velocity, a is acceleration, and t is time

 

Since u is 5m/s along the positive x axis so u = 5i. We are asked to find the time when maximum x coordinate is reached. This is also the time when the x component of the velocity reaches zero:

v=0

a (at maximum x) = -3.0i

Therefore

0 = 5i - 3i * t

t = 5/3 sec

Maximum x is reached at 5/3 sec

 

Equation 1 with x&y components is:

v = 5i + (-3i * t + 4.5j * t)                                                ---> 2

Substituting t = 5/3 so get v:

v = 7.5 j m/s

 

Now we have the velocity, we need to find the position x. We know that:

v = dx / dt

Therefore equation 2 becomes:

dx / dt = 5i +(-3i * t + 4.5j * t)

By integrating we get:

x = (5t)i -((3.5t^2)/2)i +((4.5T^2)/2)j

 

Now substituting t = 5/3:

x =(125/35)i + (81/100)j

 

 

Answers:

v = 7.5 j m/s

x =(125/35)i + (81/100)j

 

The velocity of particle is 7.5j m/s and the position is 12.5 m towards the y-direction.

Given data:

The initial velocity of the particle is, u = 5.0 m/s.

The acceleration of particle is, [tex]a = (-3.0i + 4.5j) \;\rm m/s^{2}[/tex]

The given problem is based on the concept of velocity, which is expressed at the change in position with respect to time.

We have, acceleration at time instant t. Then for maximum x, the acceleration is expressed as,

a = (-3.0i + 0)

a = -3.0i

Now, obtain the time from the equation,

[tex]a = \dfrac{u}{t} \\\\t = \dfrac{5}{3} \;\rm s[/tex]

Now use the first kinematic equation of motion to obtain the velocity as,

v = ui + at

[tex]v = 5i +(-3i+4.5j) \times \dfrac{5}{3}\\\\v = 5i -5i+(4.5j \times \dfrac{5}{3})\\\\\v = 7.5j \;\rm m/s[/tex]

Now, position x is obtained as,

[tex]v = \dfrac{dx}{dt} \\\\\int dx =\int vdt\\\\x = v \times t\\\\x = 7.5j \times \dfrac{5}{3} \\\\x = 12.5j\;\rm m[/tex]

Thus, we can conclude that the velocity of particle is 7.5j m/s and the position is 12.5 m towards the y-direction.

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