A.The swimmer pushes the water
C. the walls force against the ball
Answer:

Explanation:
Newton's 2nd Law relates the net force <em>F</em> on an object of mass <em>m </em>with the acceleration <em>a</em> it experiments by <em>F=ma.</em> In our case the net force is the friction force, since it's the only one the skier is experimenting horizontally and the vertical ones cancel out since he's not moving in that direction. Our acceleration then will be:

Also, acceleration is defined by the change of velocity
in a given time t, so we have:

Since we want the change in velocity, <em>mixing both equations</em> we conclude that:

Which for our values means:

Answer:
Earth's crust is covered by a densed air blanket called atmosphere. Due to which we feel warm even during night when there is no sun. The air near the atmosphere is less dense compared to the air near our crust. Similarly we can experience high pressure near the atmosphere comparelatively we experience less pressure near crust. The presence of atmosphere above us makes the wind fair sometimes stromy and also helps in pteperation of wind and breezes in earth's surface.