Figure 1 shows a runner using a smart watch and a mobile phone to monitor her run - AQA - GCSE Physics Combined Science - Question 1 - 2019 - Paper 2

To find the deceleration, we need to calculate the gradient of the velocity-time graph during the deceleration phase. The runner's velocity changes from 2 m/s to 0 m/s over a period from 20 to 30 seconds:

Gradient = ( \frac{\Delta v}{\Delta t} = \frac{0 - 2}{30 - 20} = \frac{-2}{10} = -0.2 \text{ m/s}^2 )

Thus, the deceleration of the runner is (-0.2 , \text{m/s}^2).

1. There are no wires to get tangled or disconnected.
2. It allows easier movement of arms which can enhance the runner's performance.

The equation linking frequency (f), wave speed (v), and wavelength (( \lambda )) is given by:

[ v = f \times \lambda ]

Using the equation ( \lambda = \frac{v}{f} ):

[ \lambda = \frac{300000000 , \text{m/s}}{2400000000 , \text{Hz}} = 0.125 , \text{m} ]

Thus, the wavelength of the electromagnetic waves is 0.125 m.

1. The power is not too great, so the battery will not drain quickly.
2. The range is sufficient for most uses, typically up to 10 meters.