The component of waves must have same frequency and phase.
when the component of waves vibrate at the same rate and attain maximum point at the same time, reinforcement of the waves amplitude occur to cause a constructive interference.However, when the two waves are out of phase where one is at minimum when the other is at maximum a destructive interference happens.
Answer:
F = 120 N
Explanation:
Given that,
The mass of a runner, m = 60 kg
Acceleration of the runner, a = 2 m/s²
We need to find the force provided from her legs. The formula for force is given by :
F = ma
Substitute all the values,
F = 60 kg × 2 m/s²
= 120 N
So, the required force is equal to 120 N.
Option (d) is correct.
Distance is the total path length covered by the object.
so, for distance, we add all the path lengths
Here the total distance =7+5+2 =14 km