Question

The position of any particle is given x=2.5t^2-7.5t.find the velocity at t=2s and 3s

Answer 1

Please refer the attachment

Answer 2

Slope of dx/dt gives us velocity
X = 2.5 t^2 - 7.5t
dx/dt = 5t- 7.5
At t=2 sec, v= 5(2) -7.5
v= 2.5 m/s
At t=3 sec, v= 5(3) - 7.5
v= 15- 7.5 = 7.5 m/s