The sound waves travel because of the pitch of the note so the window rattles.
Explanation:
A distance-versus-time graph gives the distance an object has traveled after a given time.
In a distance-versus-time graph the slope represents the the speed of the object because
is

And how steep the slope of the distance-versus-time graph is tells us how fast an object is moving; steeper the slope greater the speed. For example, a graph with slope 10 represents a greater speed than a graph with slope 2.
So the steepness of the slope of the distance-versus-time is the speed of the object, and greater the slope greater is the speed.
Answer:
400 N
Explanation:
Due to action-Reaction, the wall pushes back on the person with a force of equal magnitude and in opposite direction to the force exerted by the person.
So the magnitude must be also 400 N.
Vehicle weight shifts can be backward forward. In this particular case accelerating to fast would cause a shift of weight backwards. Breaking too quickly on the other hand would cause weight to shift forward. You have seen this while in a car or a bus at the traffic light. As the vehicle breaks you are pulled forward as it starts moving you are pulled backwards.