At what point on this position-time graph is the instantaneous velocity equal to zero? 1. a' 2. b 3. e 4. d

The correct answer is D.

The instantaneous velocity of a body is given by the gradient of the tangent drawn to the point in the position- time graph.

The tangents drawn to points A and B  slopes upwards  and thus have a positive gradient, showing that the particle has velocity in the positive direction.

The tangent drawn to point E slopes down wards  and hence its gradient is negative. The velocity of the particle is also finite at E, but in opposite direction to that at A and B.

However, point D lies at the top of the peak in the position- time graph. A tangent drawn to the point D is flat and parallel to the time axis. The gradient of the tangent is zero, implying that the velocity of the [article at D is zero.

Thus, from the position- time graph, it can be seen that the velocity of the article at D is zero.

the amount of current in the coil