Answer:
The length of her shadow is changing at the rate -2 m/s
Explanation:
Let the height oh the street light, h = 22 ft
Let the height of the woman, w = 5.5 ft
Horizontal distance to the street light = l
length of shadow = x
h/w = (l + x)/x
22/5.5 = (l + x)/x
4x = l + x
3x = l
x = 1/3 l
taking the derivative with respect to t of both sides
dx/dt = 1/3 dl/dt
dl/dt = -6 ft/sec ( since the woman is walking towards the street light, the value of l is decreasing with time)
dx/dt = 1/3 * (-6)
dx/dt = -2 m/s
The cart with speed increasing to the right ... cart-b ...
has a net force to the right acting on it.
The others ...
... Cart-a has no net force at all acting on it, so its speed isn't changing.
... Cart-c has a net force toward the left acting on it, so its speed
toward the left is INcreasing. (That's the same thing as its speed
toward the right DEcreasing.
Answer:
electromagnetic waves need a medium to travel through
They are both a form of wave, yet one is a physical wave, meaning the water wave, and the other is simply a sound.
