Answer:
When a light wave goes through a slit, it is diffracted, which means the slit opening acts as a new source of waves. How much a light wave diffracts<em> (how much it fans out)</em> depends on the wavelength of the incident light. The wavelength must be larger than the width of the slit for the maximum diffraction. Thus, for a given slit, red light, because it has a longer wavelength, diffracts more than the blue light.
The corresponding relation for diffraction is
,
where 
is the wavelength of light, 
is the slit width, and 
is the diffraction angle.
From this relation we clearly see that the diffraction angle is directly proportional to the wavelength of light—longer the wavelength larger the diffraction angle.
Jenny is traveling southward. In order to stop, she needs a northward acceleration.
A better way to say it:
Jenny is traveling southward in her bumper car, so the direction of her velocity is south. In order to reduce her velocity to zero, a velocity of equal magnitude but directed north must be added to it. Then the change in velocity is positive northward, and the change in velocity per unit time is acceleration.
South it is the same direction the car is already moving
It is called air pressure
