Question
Activity: 1. At t=0s. a particle moving in the x-y plane with constant acceleration has a velocity ofoverrightarrow (v)_(i)=(3hat (i)-2hat (j))m/s, and is at the origin. Att=3s, the particle's velocity is overrightarrow (v)_(f)=(9hat (i)+7hat (j))m/s. Find (a)the acceleration of the particle (b) Its coordinates at t=3s
Answer
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Rowan
Master · Tutor for 5 years
Answer
(a) To calculate acceleration: ### \(a = \frac{(6i+9j) m/s}{3 s} = (2i + 3j) m/s^2\)(b) To find the the trajectory coordinates at `t=3 sec', substitute
in the position vector.## Calculating x-coordinate:###
## Calculating y-coordinate:###
Therefore, the coordinates at
are (18i, 7.5j).
Explanation
## Step 1: Find the acceleration.The formula to find acceleration is
, where
refers to the change in velocity, and
is the time interval. To find the change in velocity, calculate
= (9i+7j)m/s - (3i-2j)a = (6i+9j)m/s. We're given that the time interval,
, is \(3sec). ## Step 2: Find the coordinates.The position of the object at any time
when it starts from rest is given by the equation
, but here, since the body is moving in the xy-plane, we can write the position vector as components namely:
.### The formulas for landing points are: \(x=ucos(\theta)t + \frac{1}{2} acos(\theta) t^2\) and \(y=usin(\theta) t - \frac{1}{2} gsin(\theta) t^2\).Here, \(u = v_i= 3i - 2j = (3,-2)\) and \(a = (2i+3j)\) From the problem statement, we know that at
, the initial position,
.The exact angle of the initial velocity can be ignored because we only need the x and y components of the velocity.