A ball moves on a smooth floor in a straight line with a uniform velocity 10 m s-1 for 6 s. At t = 6 s, the ball hits a wall and comes back along the same line to the starting point with same speed. Draw the velocity-time graph and use it to find the total distance travelled by the ball and its displacement.

The velocity-time graph for the motion of ball on a smooth floor in a straight line is shown below:

otal distance travelled = distance travelled in the first 6 s + distance travelled in next 6 s.

As we know, Distance = velocity × time

Substituting the values in the formula above we get,

Distance when the ball moves towards the wall = 10 m s^-1 × 6 s = 60 m

Distance when the ball moves away from the wall = 10 m s^-1 × 6 s = 60 m

Total distance = 60 m + 60 m = 120 m

Displacement = distance travelled in the forward direction – distance travelled while coming back
= 60 m – 60 m = 0

∴ Displacement = 0 as the ball comes back to the initial place.