Figure 3.23 gives the x-t plot of a particle executing one-dimensional simple harmonic motion. (You will learn about this motion in more detail in Chapter14). Give the signs of position, velocity and acceleration variables of the particle at,

t = 0.3 s, 1.2 s, – 1.2 s.



The given figure represents simple harmonic motion (SHM).


Acceleration of a particle in simple harmonic motion is given by,


a = -ω2x ………….. (1)


Where,


a = acceleration/deceleration


ω = angular frequency


x = path distance


And v = r ω


Where,


v = velocity


r = radial distance


From above graph,


At t = 0.3 s (lies between t=0 and t=1),


Position, x is Negative,


Velocity, v is Negative (negative slope), and


Acceleration, a is Negative (from equation 1)


At t = 1.2 s (lies between t=1 and t=2),


Position, x is Positive,


Velocity, v is Positive (negative slope), and


Acceleration, a is Negative (from equation 1)


At t = -1.2 s (lies between t=1 and t=2),


Position, x is Negative,


Velocity, v is Positive (negative slope), and


Acceleration, a is Positive (from equation 1)


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