What is its velocity? What is its acceleration?

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3 Answers
Feb 10, 2018

x(2.5)=3.435x(2.5)=3.435
v(2.5)=-1.91v(2.5)=1.91
a(t)=-2a(t)=2

Explanation:

It is given that the displacement xx at time tt is given by x(t)=1.96+3.09t-t^2x(t)=1.96+3.09tt2.

At t=2.5t=2.5, the displacement x(2.5)=1.96+3.09*2.5-2.5^2=3.435x(2.5)=1.96+3.092.52.52=3.435.

The velocity vv is the derivative of displacement xx with respect to time tt, or v(t)=dx/dt=3.09-2tv(t)=dxdt=3.092t. Thus, the velocity at time t=2.5t=2.5 is v(2.5)=3.09-2*2.5=-1.91v(2.5)=3.0922.5=1.91.

The acceleration aa is the derivative of velocity vv with respect to time tt, or a(t)=(dv)/dt=-2a(t)=dvdt=2. Since it stays constant regardless of the time, the acceleration at time t=2.5t=2.5 is -22.

Feb 10, 2018

The particle moves according to the equation, 1.96 + 3.09t - t^21.96+3.09tt2
so,
x=1.96 + 3.09t - t^2x=1.96+3.09tt2
Velocity is the rate of change of displacement, xx
therefore, v=dx/dtv=dxdt

v=(d(1.96 + 3.09t - t^2))/dtv=d(1.96+3.09tt2)dt

v=(3.09-2t)m/sv=(3.092t)ms

Now, acceleration is the rate of change of velocity, vv
therefore, a=dv/dta=dvdt

a=(d(3.09-2t))/dta=d(3.092t)dt

a=-2a=2 m/s^2ms2

Feb 10, 2018

Given, x=1.96+3.09t-t^2x=1.96+3.09tt2

at, t=2.50t=2.50 ,s=1.96+(3.09*2.50)-(2.50)^2=3.435 ms=1.96+(3.092.50)(2.50)2=3.435m

differentiating the equation w.r.t time,we get,

velocity =(dx)/(dt) = 3.09 -2tdxdt=3.092t

So,at t=2.50st=2.50s its velocity is 3.09 -(2*2.50)=-1.91 m/s3.09(22.50)=1.91ms

And,differentiating it one again we get, acceleration= (dv)/(dt) = -2 m/s^2dvdt=2ms2

ALTERNATIVELY

You can compare the equation with, s=ut -1/2 at^2s=ut12at2

So,you can rearrange as, x-1.96=3.09t - 1/2 ×2×t^2x1.96=3.09t12×2×t2

So comparing we can say,it had an initial velocity of 3.09 m/s3.09ms(at t=0t=0) acceleration is -2 m/s^22ms2 and at t=0t=0 it was 1.96 m1.96m to the left of origin i.e along negative XX axis.