6) The graph in the figure shows the position of a particle as it travels along the x-axis. x (m) 4.0- 2.0- t (s) 1.0 2.0 3.0 4.0

This is a x(m) - t(s) graph which is also called as position time graph.  As the body is moving on x - axis. And it starts with position of -3m on x-axis. The position of the body is decreasing with constant speed that shows that the object is moving with almost constant speed towards positive x - axis.

dx/dt will give the slope of the curve and when this curve is parallel or slope is zero then the speed of the body becomes equal to Zero.

The speed of the body can be found by the slope of the curve

A) At t=0 sec the position of the body is at -3m location of x axis. The speed of the body is not zero. at this point.

B) At t=1 s the body is crossing the point 0 on x-axis but speed is not zero it is almost constant.

C) At t=3 the speed of the body is still constant as the slope of the curve is almost same as before.

D) At t = 3 the slope of the body becomes 0 and thus the speed also becomes 0 m/sec(This is correct option)

E) At t=4 sec the speed of the body becomes less than zero that is it starts moving in opposite direction.